Unable to change Country or Region on App Store

Please help, I can't seem to change the Country/Region on my iPhone. I used to live in Canada and my Apple ID was connected to a Canadian card. That was a year ago now I live in Mexico and the Canadian credit card has insufficient funds. I'm trying to change the credit card to a Mexican credit card but I can't change the Country/Region. I'm told i have an owing balance and I need to pay that to change my country or Region, but I cant pay that since my payment method has insufficient funds, and I can´t use my mexican credit card because I cant change my country or region, so im in vicious cirlce. how can i get around this? I was told by Apple Support to use a gift card, so I went ahead and bought a couple of gift cards to cover the balance, only to find out I couldnt use gift cards bought in Mexico since my account storefront is on the Canada country.

How can I fix this?