How can I extend or reissue an expired in-store gift card?

[TML]

I have a customer whose gift cards have expired and I want to either extend the validity date of her existing gift cards or cancel and reissue them. The gift cards were bought in-store via our POS system and I have no way of identifying the transaction as we don't have original receipts or a date of issue. Any help would be most welcome. 

Many thanks, Antonia 

[HKJ]

You can search the gift card through the code, and change the expiration date.

You will search for the code in Shopify admin (browser or app, not POS).

It can be found under Products ➡️ Gift cards ➡️ Issued gift cards.

When you find the correct card, click on it, then in the expiration date to change it.