Recently I was served a drink at the pub where I intended to pay by debit card and had no alternative payment method available (e.g. cash).
The card reader was faulty and I consumed my drink whilst the barman was attempting to fix the reader. Consumption of the drink before payment was with the barman's consent.
In the end, the card reader was fixed, but if the vendor cannot accept payment for a non-returnable product and the consumer intended to pay, then is the payment waived and the product free?