[Shasown]

Why not ask the cashier to suspend the transaction,(cashier if she knew her job should have offered to do that anyways) and then sod off home get extra money or bank card, come back and pay then take your shopping home?

Which store was it Vicky?

See if they have an online page where you can compliment or complain. In this case complain about the way you were spoken to by the cashier, using the words shoddy or abysmal customer service.

Make sure you do leave an email addy though as they will often send you a voucher to use in their shops.