Stick with it Martin,it is worth it when you get them back.(Just done a 30 mile cruise round on my own in the pouring rain!!!!WHY??because I can,,new paint or not.Part of the curing process )
Your problem is with the people involved and not the car itself.Try to hang on to that thought
Make sure they don't throw that bracket away for mounting the tank straps. You should have two of them welded to the boot floor. If you don't have any replacements you will need the old ones.
I know of someone who chucked theirs and I very nearly did the same myself when I replaced my boot floor. Easily done I should imagine.
I hope the resto runs smoothly from here onwards. I look forward to seeing it.