Agreed ^^^ Also one thing to know about Mexico is unlike the US where its super easy for people to do partial or even full creidt card refunds on the spot, usually in Mexico the credit card merchants do not allow refunds, even if your credit card does. The way this is handled is they give you cash or bank transfer as money back. It's possible (though not certain) may not have been fraud, but simply a cultural misunderstanding where they thought they were going to get your bank details or give you cash at a later time and you simply assumed it was going to be 6000 pesos back to your card.
Either way if you file a chargeback the chance of them fighting it or even knowing how to respond back is virtually zero. With the exception of Mexican airlines if you file a chargeback in Mexico you will most likely win by default.