Joined: Jan 2010
Posts: 9,811
Likes: 1,787
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
I would drill out a short depth of the bb spindle threads and tryu again.
Oil the threads and try starting the bolt in. If it immediately binds, I would tap the bolt with a hammer and try turning again, repeating this hammer-and-turn process in an attempt to get the bolt threading smoothly.
What is the shop's story? They buggered the threads?
One fix would be a YST "threadless" bottom bracket, which is inexpensive and threads into itself so no bb shell threads are needed.