If it's taking that long and requiring that much effort.... at least I'm assuming the bike shop is making some effort to work on the bike, then this is probably going to already cost you more than all the pieces parts are worth.
Maybe you just need to cut your losses and go a different direction. Not all bike shops are equal in their abilities to work on anything that is slung at them. Some are only remove and replace type shops for things that are already in decent shape. And only for the lines of bikes they sell. Which is not a bad thing in itself.
But those places might not be equipped or even have experience with what you've dropped on them. Are you certain your bike shop is equipped and experienced for anything?