Folks just don't seem to realize: you make a reasonable effort with the vendor, and then go straight to your credit card company.
I caught a restaurant "helping" themselves to a very healthy tip for delivery; I'd tipped in cash. The owner repeatedly professed that he didn't know how to issue a refund and offered cash.
He was playing stupid because he didn't want to deal with the transaction fee, nor did he want a paper trail of his fraud; I strongly suspect he was doing this to other people, too. Warned him three times and three times he said, gosh, he had no idea how to issue a refund to my card.
I asked for just the fraudulent tip back and my credit card company reversed the entire charge. So not only did he lose the tip, he lost the cost of the food and he got dinged with a chargeback fee. He also lost my weekly pizza order.