The four months thing is a canned response. It may or may not be that long. So don't get hung up on that.
As for it being ridiculous, as it's been pointed out before, processing in London right now is quoted at 11 months. That means 80% of applications are processed within 11 months of them arriving on London. Yours arrived in London probably mid-January. You're at about 9 months. You are also non-visa exempt, which almost certainly means your application is going to be on the longer side of average.
You can look at the spreadsheet to get this information. The Notes column has details of what documents were requested. The spreadsheet is there to answer these sorts of questions, please use it!