In 2013 we had our newly bought outdated house completely renovated/extended. My wife was pregnant at the time and we made a rushed decision of either waiting until our children were a little older to carry out the huge amount of works or get a company to do it there and then without thoroughly researching... Through local recommendations, we found a company that gave us a good price and were able to start within the 2/3 months mark of the initial meeting. It took the company around 4 months to complete the job (we naively let the owner project manage everything from submitting plans to meeting with the building inspectors) however very soon after the works were complete and we received our building reg certs, we noticed foul drain smells coming out from our newly extended kitchen/diner floor and newly created bathroom (we even have rats continuously crawling under the kitchen....) Long story short, we had the company out many times to try and rectify the issue but were unsuccessful (We even had drain CCTV performed twice at our own costs which showed no issues). From August 2013 until December 2015, I had continuously tried to speak and email the owner to rectify the issue but he basically said in the end he had no other options and ways to resolve the issue. After my last email in December 2015, I decided I cannot expect a change around from the owner and I now had to cut my loses and get a company in to rectify this problem. Since then we have had a few construction companies in and they have advised us the flooring was incorrectly laid, issues with ventilation and the drain smells issue seems as if there is either an uncapped old unused drain or/and issues with the drain pipes. A couple of the companies said they were even surprised that building control had signed this job off (especially when it came to the ventilation issue). I am now thinking maybe I should find out what went on with building control as I never got to see them during their visits (both my wife and I was working) and we have heard the company owner and inspector are very good friends and may of not even made any visits that required thorough inspection... Has anyone else been in this situation before and how would you tackle it?