Sorry, this is an too oft told story and I'm a long winded guy. I suspect a lot of things can change from Josh's post from 2018 to the present. I know not everyone has the time tools, physical flexibility or inclination to do their own restoration to the level they desire. But if you have time and inclination ( get help with the physical part if needed) I asure you that unless you are working with seriously bent or rusted out frames you can probably buy the necesary parts, tools and learn from the internet, library, local club expertise, classes etc. and restore your car possibly in less time and certainly for less money than some shops may require. For example, you can paint a small car, build a spray booth, buy a big enough compressor, spray gun or two, good respirator , sanding materials and paints for a quarter of what many shops will charge for a quality paint job. Then when you make some mistakes and want to do it again, you will still save money. Your level of satisfaction will be immense and you will know your vehicle inside and out which will serve you well on the road.
Never tell a shop owner to work on it when they are slow for work in the hope of saving a buck or a pound or a euro. Panel beating is 75% skill and 25% understanding and is the key to a decent restoration. Take a metal working class, shoot, take three classes and buy some hammers and dollies, a combination mig/ tig welder. You do not need top of the line stuff. It's really the " feed a man a fish versus teach him to fish" thing. Sure, send the engine out for overhaul or for the machine shop work that is beyond most do it yourself folks. You basically have to send out the block, crank, cam and head and other stressed parts for inspection and rework. A couple of torque wrenches and some feeler gages and assembly is actually fun.
I worked in aircraft shops for much of my career and we never led a customer on as has been described here. If we took on a project we worked on it until it was done after an accurate assessment of the scope required. If unforseen things happened, the first thing we did is get on the phone to discuss a situation. It's called customer service and it is really simple and usually makes everyone happy, even if it's bad news. If they wanted to go elsewhere, so be it. Often it became a regret that they just didn't like the truth we gave them. We shouldn't have to settle for less......IMHO.