Unacceptable work done

I would never recommend Black brothers they do not take ownership of the poor workmanship and awful customer service.Never stick to time frames and makes the customer wait qnd to jo apologies. They put up a roof up ,waterproofing and a ceiling a month and half ago..The workmanship is absolutely of below standards on all work done.My roof is pooling and roof is very bouncy not stable.The ceiling was not creted correctly so many bumps etc Although no leaks for now the pooling on my roof and the stability of roof is of very poor workmanship.When asked the owner to visit the site prior to work being completed numerous occasions due to thei poor workmanship the owner not once appeared on site.He only appeared on site when last deposit was given and was only 2 weeks later They did not adhere to the quote.All they have to say about the roof is that it is water tight and the pooling on my roof is absolutely no problem and stability good.The problem was they did not get the slope correct and now the client sits with a problem of mild dew,algae and sagging.on the roof and due course the roof will collapse.