Customers at Sainsbury’s have been unable to use their Nectar vouchers due to a technical error.

Customers who use the supermarket’s Nectar card receive one point for every £1 spent in-store and online.

You can exchange your points for vouchers; one Nectar Card point is equal to 0.5p.

Sainsbury’s trialled The Big Points Swap in April, where you could exchange points for vouchers worth up to twice their monetary value.

If you had 2,000 Nectar points, you could exchange them for vouchers worth up to £20.

2,000 Nectar points are normally worth £10 in vouchers.

According to Sainsbury’s, the Big Points Swap deal was only available to a “small number of customers.”

However, some customers have been unable to pay for their groceries at the register because the vouchers they received did not work.

Debbie Craig, a shopper, exchanged 12,000 points for a £60 voucher, but she claims she has been chasing Sainsbury’s about her voucher issues since April.

“This has been a complete disaster,” she told.

“I’ve spent weeks trying to figure this out and have hit a brick wall.

Other shoppers have complained about the same issues on social media.

One customer was “very dissatisfied” when they discovered their vouchers weren’t working.

They took to Twitter to express their displeasure, writing, “Can you explain why my big points swap for £20 barcode isn’t scanning at @sainsburys?”