Recourse for travel agency error?

Here's the situation: my brother is getting married in August in Mexico (destination wedding thing), and he used a travel agent for setting up the room block package, etc. But I didn't reserve hotel before the group rate expired. Fine, no problem: I paid the higher amount without question; paid in full with credit card. Nearly a week after i paid, i get a call from said travel agency stating they messed up, and the person who booked my trip gave the wrong info, etc. (And this is after my card got charged, and i received electronic receipt.) I've been hassling with this travel agency because they don't want to honor the price that I paid, citing that they know its their error, but "they can't do anything about this", and i have to pay an even higher hotel room amount. It sounds fishy to me at worst, and negligent at best. Besides the obvious full refund, do i have any recourse here? (And, yes, i know travel agencies suck in general, but was going along with what my bro had set up.) Any suggestions, or should I just give up and get refund???