if rental place is not upholding their end of the contract then sounds like it goes to you aka you get everything and the contract title so on cause the rental person place is violateing laws.

If it comes to it, anything with an 18% hydrogen peroxide base can kill it off, then use a high-strength, preferably industrial, disinfectant to follow up with. That with serious dehumidification will kill off mold and help keep it from coming back.

the problem is, the plumbing leaks right there so its constantly wet.
keeping the mold alive.

If there not getting back and taking it srsly u get all the paperwork you need and go to someone who can force them to fix it. Dont pay them either thats not inhabitable and as such you shouldnt be paying. If u need to get the police involved cause there not upholding the contract.

Ugh, black mold... Hopefully it’s the nontoxic kind, but regardless.
Keep taking pictures and save emails from contacting your host. Try to visit a doctor or health clinic and get evaluated for illness. Do everything you can to create a paper trail.
Most cities have a non-emergency phone number; if worse comes to worse (which sounds like it already has), call and report a health code violation.

At this point, I suggest getting advice regarding this situation for your local state's environmental health department.
I'll provide you with a jump start.

This link is a page summary of what you should be aware of and what you should do; please read it:
https://www.nolo.com/legal-encyclop.....ion-30230.html

This link is a database of bills/laws listed by state:
http://www.ncsl.org/research/enviro.....-database.aspx

On the Database page, look up "Indoor Air Quality – Mold", your current state, and select Year "All".
This action should give you related legal information to help you understand the available laws in your state that can help you regarding this mold situation.

I wish I could do more, but this is the best suggestion that I can provide for you at this time.
Good luck and best wishes; I'll be here if you need advice~

Are you in the U.S.?
Here, this place has some info on how to deal with landlords that won't fix stuff... https://realestate.findlaw.com/land.....d-repairs.html

Mold like that is indication of moisture build-up, which could indicate there is water leakage in that area. Such problems must be addressed by the landlord!

Also, that looks like active mold, and it will NOT GO AWAY simply by cleaning. The source of the moisture that's promoting the mold growth must be dealt with!

That is not acceptable at all. I'm sorry you've been having to deal with it.

Print off your messages to them that have no replies (I am guessing email here?), take the photos as you have and inform the relevant authorities (I don’t mean police; depending on where you are could be public health). Alternatively, although the black mould itself isnt toxic, the spores are so you can take your landlord to court for knowingly exposing you to something that will affect your health.

With many landlords, they will be responsible for fixing the route cause but you will be responsible for keeping the house clean, mould is just one thing that you should be keeping on top of so beware that he/she (the landlord) could make the argument that you have not kept the house in a clean state (just something to be aware of). As mentioned above you can buy black mould cleaner which contains bleach and will easily clean this for you, I recently cleans a smaller scale mould from my bathroom.

TLDR keeping it clean is likely your responsibility but the route cause will be your landlords responsibility. I hope this helps :)

Call your county health department, they will make your landlord fix it.

Spray it down with diluted bleach.

Call local code enforcement and see if they handle vagrant landlords since the repair hasn't ben handled in a certain time frame it could count as vagrancy. Have all your calls, texts, and emails documented and ready to hands over if needed. If they can't help they might now who you need to contact and start the process for the city, county, and state to be able to fine the landlord. The government always wants more money.

Black mold!?

Ugh. That plumbing needs to be fixed first, then the sheet-rock and insulation
needs replacing as well as the floor around that leak.

Boy, that'll run ya.

No, I'm not an expert about this. My mom and I lived in a mobile home that grew
such underneath the bathroom... until we moved out of it. Black mold is some
nasty shit you don't need. The other commenters above my post have the better
information than I. You need to get a LOT of help with that fungal
biological hazard and get it, as well as the its source, gone.

For a safer and less compromising method of managing the mold, use Hydrogen Peroxide. Get a mask (This is just because of the mold by itself) so you don't have to breathe it in up-close, then spray it on all mold areas and let it sit for 10 minutes before scrubbing the surface. It won't stop the problem, but it will nullify it and at least make the area a little safer. Also, don't dilute the Hydrogen Peroxide or it will be no different than spraying the wall with water.

Hydrogen Peroxide is one of the most powerful cleaners most people have in their homes, yet don't really use at all. Spray it on any part of your body and you'll know immediately if it's clean or dirty by the instant chemical reaction: bubbling. Use it on grout between tiles and you'll probably see it become whiter than usual.

And since the scent and air will have contaminants, I strongly advise going to a Dollar store and buying a lot of Moisture Eliminators and place them in every corner of your home. The ones with Charcoal preferably if they have it. Those actually will help manage the water damage and keep the air crisp. I have 4 in my room at this moment and probably won't be needing to replace them again until next year.

Facts: From what I've learned from my usage of them for the past year is that they absorb more moisture in areas that are really dense in it. So putting them right were the mold is should make it recede faster. So I would advise doing that.