Frank Williams, of Stirchley, Telford, was left flustered and in a panic when his debit card was declined while doing his shopping at Home Bargains on Wrekin Retail Park.
The 71-year-old had been the victim of a scam where more than £200 was taken from his bank account and had been misinformed about his new card details.
But to his rescue came a stranger from behind who parted with her cash to pay for his items.
"I started to turn red and sweat, I was very flustered and didn't quite know what to do," he said.
"It's an embarrassing situation to be in, but then this kind lady asked how much it was and offered to pay for the lot.
"She was quite young and had three children with her, I told her not to worry but she insisted she pay.
"It was only just over £11, but that's a lot of money to some people and an incredibly thoughtful gesture nonetheless."
Frank waited outside for his mystery saviour but missed her pass, and now wants to repay and thank her for the selfless act.
"I'm still thinking about it days after, it's amazing to know there are still some kind people out there," he added
"I didn't have any cash with me as I'd just come from the allotment, so I don't tend to carry much in case it gets lost.
"I went to the bank straight after and they told me my PIN had not been updated so I obviously couldn't use the card.
"It happened all so quickly there's not a lot I can say, it was just such a great relief.
"This lady must know who she is and I'd certainly recognise her. If she could get in contact with the paper I would love to be able to thank her in person."