With some gift cards it will decline if your purchase exceeds the amount left on card. I'm a grocery clerk and see this all the time with these cards. I can usually get around it by putting in the amount left on card manually.

Fortunately our system allows us to look up the balance on those cards and have no problem processing with the split card option on our registers. With private gift cards the customer has to know the balance in order to process the purchase using split card, which allows me to enter an amount to be taken from card.

Unfortunately never found a way to solve that. It could be the card that is damaged either the strip or the chip. So it will not read correctly. Do you have the option of maually entering the card number? I have seen this for years and have always thought it to be theft by the companies that sell those cards and believe they know it. It has gotten better but still too many of these stories like yours.

Online accounts in reality should be easier to correct. Sorry this is not true for you.

Edit to add: you can file a complaint with the FTC. Don't know if this helps.