Feisty grandad Robert Hoare prompted a High Street stand-off with shop staff after swapping what was a defunct gift card for new earphones at HMV in Lincoln.
The 61-year-old said he was "standing up for all those who had lost out" after the beleaguered chain originally announced it would not accept vouchers from customers.
Mr Hoare slapped the £25 card on the counter and left the shop with four packs of earphones.
Staff called police, but he kept the goods after officers said it was a civil matter.
Mr Hoare, who left his name and address with staff, staged his protest on Saturday, January 19, after HMV entered administration.
Thousands of shoppers faced being left out of pocket when the company said it would not honour gift cards.
However, administrators have since announced a U-turn on the policy and said vouchers could be redeemed from Tuesday, January 22.
But Mr Hoare was not to know this when he risked arrest with his defiant act.
Mr Hoare's grandson, Josh Smith, 18, is a paper boy earning £30 a week. His card was actually issued by HMV as a refund.
Mr Hoare, from Rowston, near Sleaford, said he was not afraid to have risked arrest to speak up for all who have lost out.
"I did this for my grandson and all those kids who have not been able to spend their vouchers which people bought for them in good faith," he said.
"Josh works six mornings a week in all weathers delivering papers and the £25 at stake here is nearly a week's wages for him.
"The police took the view that this is a civil issue, not criminal, and that they are not prepared to take it any further.
"Had I been arrested, I would have denied theft and gone to court to give publicity to all those kids who have lost out.
"I have proved my point and I wish more people would take a stand on this.
"HMV should let us spend what is ours."
Mr Smith, a catering student from Peterborough, thanked his granddad for his direct action.
"Good on grandad for what he's done," said Josh.
"People have paid for these vouchers and HMV should accept them.
"It's us who have paid people's wages."
Josh had been given a £150 voucher refund at the Lincoln store after spending his birthday money on a tablet computer which became faulty.
No replacement was available so a gift card was issued because Josh didn't have a receipt.
When news of HMV's problems broke initially, Josh dashed out to spend as much as he could on games, CDs and DVDs, leaving a £25 balance.
Then on Monday, just 48 hours after Mr Hoare's very public protest, HMV's administrators performed a u-turn and revealed they would now accept gift cards.
So, does he think his stunt was responsible for the change of heart?
"Egotistically, I think that it was all my fault that they changed their minds," he said.
"If not, I played a small part. It is coincidental that I staged my protest on a Saturday and they changed their minds on a Monday."