Just came across another instance of DCC in Mexico City. Had to go to the ER tonight, and upon leaving the hospital I was settling up and the cashier asked me if I wanted to be billed in dollars after I handed over my CAD MasterCard. I declined, and asked to be billed in pesos, and she processed the transaction as requested without hassle. I did notice, once again, the POS Terminal culprit is Santander.