There's no way to convert it without giving a discount because the gift card is inherently less valuable than cash. One possibility is to find someone you trus

There's no way to convert it without giving a discount because the gift card is inherently less valuable than cash. One possibility is to find someone you trust who is going to make a large cash purchase and ask them to use your card instead. However, I don't see why you don't just pay your expenses with the card for a month or two and bank your normal income.