Thats a tough one and I can only imagine the best way forward would be to replace the seat with something more suitable to you.
Scrapyard would be my first port of call for a replacement seat
I would be tempted to pull off the trim in the boot area which may lead you to find the problem.
Managed to resolve a similar issue on a Toyota recently and it turned out to be a plastic clip that had dropped into the latch mechanism
It would be advisable to scan the ECU to see what fault codes are stored in there.
Could be anything from engine management to ABS related faults, maybe something simple though
It looks like the vacuum hose from the Brake Exhauster which is driven from the engine.
It would be quite vital to get this sorted as soon as possible.
Looks like there are some other hoses that have some chaffing wear on them as well
The window regulator is cheap to buy and relatively easy to fit if you have basic handtools
List of parts on eBay: https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2499334.m570.l1313&_nkw=volkswagen+golf+mk7+drivers+side+window+regulator&_sacat=131090
I believe it is the turbo variable vanes which are stuck in place with carbon and needs cleaning.
Here is a link to a cleaning kit: https://www.ebay.co.uk/itm/323958600044?hash=item4b6d6ff16c:g:basAAMXQfvlSg4~P
That doesn't sound good and i would take it back to the garage who changed the cambelt to check it out.
Quite common for bolts to shear but this is not from overtightening just poor quality bolts used by VW