Damp issues - (does such a person exist?)

[idkhow2diy]

Got a damp issue in a rented house. It's upstairs, presumably penetrating damp. It got particularly bad a year and a bit ago, so much so that a plumber we had round at the time wondered if the tenant had been playing a hose on the bedroom wall. But the problem had occurred earlier.

I went through the usual mistakes. Had a survey done by someone who then wanted to strip all the plaster off, put some form of 'waterproof' render on and make good. A builder friend persuaded me to try a cheaper alternative which was some sealant which did nowt of course. Same friend got a friend (!) to change some roof tiles. Said friend of friend informed us the roof needs replacing.

We had a roofer come and tell us the roof needs replacing. He apparently did this by standing at the road about 60 feet away.

Then I had an independent surveyor check it out and he determined the most likely cause was the chimney stack. He saw evidence in the loft of water ingress in that area and the (by now) major damp was under where the chimney splits inside to serve the two bedrooms. He did not consider that the roof needed replacing, no surprises there.

The guttering was replaced with plastic soffits ('roofline') and downpipes years ago and there is no visible sign of leaks from any of that. the render has seen better days and has been patched in places but is not falling off. (why do they render brick houses! it's pebbledash stuff)

The chimney had long since been disused, fireplaces blocked off upstairs (no damp ever, I grew up in this house!). So we had the stack removed and the roof made good by a roofer we've used before on our own house. The house was built in 1935-ish, brick, cavity wall and rendered outside, all double glazed and centrally heated. It has cavity wall insulation I believe (my mum had this installed after I got married and moved out a couple of decades ago, there's no paperwork but there is evidence on the outside. Also the wall ties were replaced).

The bedrooms suffer from condensation and as it is rented and tenants generally don't care I had an envirovent thing fitted as well.

All seemed to be going the right way but now the tenant has told me it is as bad as before, even though when I inspected it last October it seemed to be getting better. I've no idea now where the water is getting in and I am considering just selling the place as none of our kids want it so it is likely to become a money sink. Sorry to ramble.

So, my question. Is there such a person that will actually make an effort to establish where water is getting in rather than just looking round and writing a report? If so, what are they called? (job title, not Bill or whatever ;) It's so annoying because if I lived there I'd probably find it.