Hi there Samantha, it's great to have you here at planDisney!
While it's always so nice to receive any Disney-related gifts from family members, I can definitely see how awkward it can be when they don't quite get it right - even with the best of intentions. It sounds like that relative got a bit mixed up between the
Disney+ Gift Card and the
Disney Gift Card which - despite being only a keyboard character different in writing - are entirely different as you definitely already know.
Unfortunately, there currently does not exist any way to directly exchange these cards for one another; the
Disney+ Gift Card US Terms and Conditions states the following: "The Cards are not refundable except as required by applicable law." While a
Disney Gift Card can be redeemed for Disney+ Service according to its own set of Terms and Conditions, the reverse currently isn't possible; you are welcome to
contact the Disney+ Help Center however, to see whether the folks there can provide you with any additional insight or assistance. (You can also have your relative check with the retailer where they may have made their purchase to see whether there's anything that they can do on their end but ultimately there might not be too much that can be done with a nonrefundable gift such as this.)
You may have heard of the case of a family that had similarly purchased $10,000 worth of Disney+ Gift Cards, who did somehow manage to have this rectified after their costly mistake was widely publicized. Here's hoping that the Cast Members you reach out to will have some solutions that they can offer you, and though we can't quite assist you with this here at planDisney I do hope that your question being published out there can help other folks and families before they befall a similar fate. That said, if you're not already a subscriber there could be a silver lining to this - with
special offers and promotions exclusive to those who do have Disney+ throughout the year. Keep an eye on
the Disney Parks Blog to see when these do pop up, and don't hesitate to come back to us here at planDisney if there's anything else we can advise you on within our domain of the Disney Parks and Resorts and the experiences you'll find therein around the world!
Wishing you all the best in hopefully having this sorted out before your trip!
Prince