Billing issues

From January 2020 I have been billed 15.99 dollars for my South African netflix account, I did not think to convert and check if it amounts to R169 for the premium version of actually amounted to just over R280.

I only realised the amount when checking my account balance this month.

When I contacted Netflix and informed them of what had happen they advised me that the Netflix account was created in a different country therefore this issue. I created my Netflix account in 2018 and paid the normal currency till December 2019. This does not make sense to have the billing currency changed from 2020 when I did not even leave the country ever. When I asked if they could refund me or credit what is due to me they said that they cannot as I should of informed them once the 1st premium was debited. I thought as an American company maybe they changed there billing system because I changed by bank account details which was previously a Mastercard and now a Visa card which could have been the reason that it changed but to the correct monetary value. This was not case and they are not going to credit or refund me.