Thank you, Freddiemercurys twin and foxhole, yes, it's a lintel. At first I thought it was my wife's secret treasure chest, but she didn't panic when I told her.
I can't raise the level 'cos I'd have no flow. I'm thinking that perhaps it'll have to be a macerator. The only other thing I thought about was to go through most of the studs in a stud wall, but I don't want to weaken the wall when I 'm going to put up 9mm porcelain.
Are the type of metal products (Metwood?) used for strengthening joists and studs any good.