Bad Services from Nation Housing

I have a bad experience with Nation Housing in the place that I stay in they built houses on plot and plan basis. The house that they built for me has a problem in winter with fungus on the walls, the walls get dirty and dump it smells and affect our health we get sick and my kids get sick because of this. Our clothing and furniture is also affected by this, we had to throw away items that had fungus that could not come out. They built with cheap material hence this and i have reported this to them a number of time and the response was i need to open the windows to allow the air to come in the house to clear the dump and wetness in the house and this is useless because it does not help. They did not put waterproofing while building the house that is where the problem is and I'm not winning with them. I bought the house in 2013 till to day nothing has been done. I have sent them to lawyers but still nothing they deny everything and they don't want to take responsibility. I don't know what else do do now and winter is approaching we are going to go through this again. I have spent money on paint trying to solves this for years now I buy paint to paint the dirty walls over and nothing works. On top of that we are expected to pay for levies every month and yet we are not in a complex there is not gate installed and we are paying for municipal rates and nation housing is asking for levies of R495 every month and i had a problem with this and told them i could not pay because I'm struggling financial and don't believe we should be paying for levies because we are not in a complex there is no secure gates, because of that they charge me interest on my account double the amount of levies every month and i have asked them to take away the interest because my account does not go down at all because of the interest they charge and they refuse to do so. I'm paying R1000 every month but there is no difference in the account. They have handed my name over to lawyers and i have appeal my case so many times and their lawyer also change interest on the account it is a mess and a battle that I'm not winning with them. I need help i believe this is not fair and they are extorting money out of me, money i do not have. Please help me sort this out with Nation Housing. Thank you.