we get that ALL the time. thats an easy one - you suspend the transaction and store the bag under the till with a signed reciept and their name and contact details why they go and get the money. people like hat are more often or not shoplifters - they distract the person at the till while their accomplice goes and nicks stuff
I quite often have to call at fuel filling stations in the wee hours when the shop is shut. If I get a s**ty assistant I'll send them on various errands around the shop to get me stuff, then, whilst they get the last bit I walk off leaving them with a stack of stuff they've got to cancel and then put back... 😂