HELP! Disputing a charge

So I bought a gift card to a large online merchant a few weeks ago and added it to my account. However, without spending a penny of it, eBay is not giving me access to it, saying it is locked on my account. I’ve gone through eBay’s gift card process to “unlock” the account at least 4 times and they keep giving me entirely unhelpful and vague answers about how they do see a card linked to my account, but that’s it, no further information at all.

At this point I feel like I’ve done everything I can, and I really just want my money back. Is this something chase sapphire usually would handle in my favor? Also what’s the process of disputing a charge like via chase?