The Unblocking of a Plumbing Problem in a Flat

My dad used to be a builder, and in his mid-twenties he moved into a single bedroom flat with his then girlfriend. He noticed that the plumbing in his flat was playing up, so he called a plumbing company to come out and unblock the drains. The plumber said it looked like someone was flushing food waste instead of binning it. A few days later my dad got home from work and as he got out of his car, two blokes approached him. They were policemen who asked if he lived with a bloke named Dennis - but My dad said no. When they told him there was another place for him to live, he thought maybe I should look