Tell your friend to double check his credit/debit card statements to make sure that they did actually charge him for the item at the time.
I bought some items from a catalogue company online & gave my credit card details only to discover about two months later they hadn't actually charged me at the time & I had to pay separately - it was rather bizarre & annoying, I still buy stuff from them and even though they have my credit card details, I still have to make payment myself afterwards.
If he has paid then he needs to contact them & tell them that he's did so and have them adjust their records.