Who to chase?

[RadoVR6]

I tried to buy a gift voucher last week with some other shopping. After my pin was accepted when paying, £80, the lady on the till said the gift card had failed to activate. The receipt came off as £80 less the £20 voucher and the bottom line was £60.
I was told I would only be charged the £60.
We then tried with another gift card, the same happened after I entered my pin but no receipt came off as the lady on the till said it was a failed transaction.
I have had the full £80 and another £20 taken from my account.
I went back to the shop and they said it would go back into my account 3-5 days time. Low and behold still nothing back.
Would my bank be able to claw it back?
I have zero confidence in the shop.
Thanks

[kentlad]

Is it a national retailer? If so, easy enough - contact customer service and threaten financial ombudsmen, they'll sort it. If it's a one man band, go back - ask to speak to the owner nicely, explain the situation and ask for a cash refund.