Roof guaranteed, but roofers now unreachable - England

In 2023, I had roof work done, on both a flat roof, and a regular angled tiled roof. The problem is regarding the flat roof, so I'll focus on that.

​

The work for the flat roof cost £4k, including some skylight work, and was guaranteed for 15 years. Last year, the roof started leaking, so I had them out to repair it. Less than six months later, it started leaking yet again. I tried to contact the roofers repeatedly, but I can't get hold of them; they don't answer my calls, they don't answer my emails, I've tried going to the premises listed as their address but can't seem to nail them down.

​

I've given up a bit and started asking around other roofers to look at the job and, depending on how deep I want to go, I'm looking at another £4k, which I just don't have. Worth noting here that I'm unemployed due to long term disability.

​

The job was paid by bank transfer, so I don't have any kind of credit card protection.

​

I'm angry that we paid £4k for work that just hasn't held up and that I can't get the original roofer to honour their guarantee. Is there a way to either get my money back, or get them to actually fix the thing?

​

Any advice would be appreciated.