Teppermans Discount

Hey everyone, wondering what you guys think about this situation.

Me and my partner were shopping online for a fridge. After finally picking one, we added it to our cart to see how much the final total with delivery would be... when we saw there was a $600 discount automatically added to our cart. We checked out and received a confirmation email, as well as proof of the same total taken out from our bank.

Next day, we received a voicemail, saying that our order was cancelled bc there was something wrong with the discount code and we saw the amount we paid pending to be returned to our card without even talking to us first.

Can they do that after we put in the order already? Or should we be doing something about it?

Thanks everyone for your advice!