BPTP — Sewerage problems

Every week, the server back fires and my kitchen gets clogged. This problem is there for almost 2 years. The entrire house stinks. You neither can cook nor eat.
Inspite of regular complaints there is no support. We are paying heavy maintenance, then also they don't do anything in regards.
This is a toucher, spending so much money and buying a flat has turned out to be a bog pain. Request to look into this matter with immediate effect.