Stop Guesswork Different Banks Different Tipos de Cambios

Finally arrived in Zihuatenejo today, went to Comercial and used the ATM's.

HSBC actually has a screen that shows the exchange rate and you have to accept or decline it. It offered 17.82, but I could have taken out 15,000.

Neither the Santander or the Bancomer stated the exchange rate, so I took 6,000 from each, and including the fees, the rate from Santander was 18.92 and from Bancomer 18.9
Obviously, the convenience of getting 15,000p out at at a time isn't worth the exchange rate!