It depends on the store you go to. I recently bought 2 cv shafts at Advance. I had to pre-pay plus core charges. When the parts came in they were the wrong size. Took me a half hour of explaining and showing them the old axle shaft compared to the new one before they refunded my money.
Then they forgot to refund me the core charge, so I had to go back a second time. They all along insisted that these were the shafts for my 86GL, even when I showed them my old ones that wete an 2 inches longer.
Ended up going to auto-zone, they had the correct part in stock.
Just remember "the customer is always right" if you are persistent.