Expired gift card which I didn't know

Good day I'm currently sitting with an expired gift voucher which was given as a gift the unfortunate part is I did know gift vouchers expires, secondly the card itself its not having any expiry Date which I feel is inconvenienting I was only told today at westgate truworths that its only valid for 3years which I understood but also explained to them why it wasn't not reedemed upto so far But all I could get is there is nothing they can do its expires so iv suffered such loss of money because of mis information that we get at the shops I feel like this needs to be attended to or there must be a way to recover the money It's a big loss To me I don't understand why must I forfeit money that was given as a gift just like that