Full transaction history?

Hoping someone can help me.

I just signed into my account to check my balance, and it was $20.96.
I clicked to redeem my gift card, which it said was successful (for $20) but now it is saying my balance is only $25.96.

I can see my purchase transactions, but nothing that shows at which point a gift card was redeemed, so for me to go back through and confirm that the balance was correct when I checked. I've redeemed 3-4 vouchers over the last few months of around $90 value, so the $20.96 balance should have been correct based on my transaction history, so naturally I am confused as to why my balance is only $25.96 not $40.96?!??

Any help greatly appreciated.