Chargeback on credit card account – money gone?

Good day everyone,

I have the following problem, for which I hope to find a solution here:

Here's a case: I rented a car from a rental car company and returned it properly.

The previously paid deposit was then supposed to be refunded to my credit card (the company doesn't "block" the deposit amount, but rather debits the entire amount (rental price + deposit). This was supposedly done, but not to credit card A, which I used to pay for the rental, but to another credit card B stored in the system (credit card is not blocked, account is active).

However, the amount never arrived on this card or account. Where did the money go? The rental car company claims to have initiated the chargeback (the dealer's receipt is available and, according to my plausibility check, is in order), and the bank claims not to have received any transfer.

How do I handle this matter now if I don't want to waste the money? What legal options are available to encourage both parties to conduct transaction research? Enough friendly questions and conversations have been exchanged. I thank you for any helpful suggestions.

Greetings Ralfredo