I've dealt with trying to train newbies who just won't be trained.
I had a cashier at my previous store who would call with some of the weirdest questions, that would be obvious with a smidgen of common sense.
She paged me once because she was trying to use a Starbucks gift card as payment. We are not Starbucks, therefore we do not accept their gift cards as payment.
Her excuse: because we sold them she thought we should take them.
She called because she ran out of $20 bills and didn't know what to do (substitute two $10 bills).
She constantly had a long line because she'd chit chat with every customer in line, then try to ring items we couldn't because we weren't equipped (no scales to weigh produce, so any produce had to go to the main grocery checkout).
Every time I tried to say something, she'd say, "I'm only giving good customer service"
...Yes, but we can't give a service we don't offer!
--Drug Store Diva