Surcharge added on NIYO card after 2 days?

Hi,

I have been charged extra charges on one of my transactions. When I checked with the Live Chat they simply say that “merchant has charged the extra amount… the surcharges are additional fees that can be added to the purchase price of goods and services. And the surcharge can be due to the fluctuation of the currency”

I was told that NIYO card is for real time currency converter… And how come the bank has approved the extra amount without my approval?

If NIYO can charge additional fees anytime, we won’t get to know when and which merchant will debit the extra charges from our bank account without any approval. This seems to be a security threat

Any others facing this issue?