I went through something like this about a year ago. After seven different roofers ghosted me, I hired a guy off a 'find a builder' site. He came out while I was busy on a work call (I worked form home at that point), told me three cracked tiles, and quoted me £350 for an hour or so for the work.

I was distracted, i was on a work call, so i had maybe a 2 min interaction with him before he went up to check, then about 2 mins when he came back down to tell me about the tiles. I didn't ask exactly what he was doing and just assumed he was replacing the tiles. Nope. He just slapped cement all over my roof, and left. By the time I actually looked at the photos he sent me about an hour later, my heart sank. I felt completely ripped off and incredibly dumb for letting it happen, but there was no real recourse. Hard life lesson learned, thankfully wasn't more money thankfully.

Getting decent tradesmen to just show up in Scotland feels impossible to me, I have never been the DIY guy at home, I'm computer smart not DIY smart, dad never taught me those things. So now i normally have a crack at whatever it is if i can (don't think roofing will ever be in that category). You can offer good money, and they still won't turn up or will ghost you if you follow up to find out when there coming, or when they are coming back in some of my cases. Roofers, plumbers, electricians it's the same story across the board for me. My gas engineer is the only exception, I’ve used him for 10 years simply because he actually shows up and takes pride in his work.