I use the wirex card as any debit card (POS), you can make online purchase with it, so it's just as any debit card. My friend also bought things in a country which the currency wasn't the debit card currency, it worked fine. The good side is, if you travel a lot you can get USD, GBP and EUR cards and all with the same company.

Regarding make a mistake, to be honest, I'm looking for another debit card because both me and my friend had our share of troubles with wirex. They do try to solve the problem, but it seems they are not very good at what they do. The app interface is bad, they changed the exchange ratio calculation a few times, their support takes days to solve any problem, my friend's card was delivered to his old address (11.000 km away), when they changed from mastercard to visa the app interface showed 2 days for the delivery time using the free express delivery but it actually took 2 weeks, half BTC disappeared from my wallet due to a bad exchange (app failure maybe?) but they did refund me after a few days. They do are improving and they do try to solve your problems, but I feel like riding in a car that is being built while we drive it down the road. For now I'm sticking to wirex, but I'm looking for better alternatives.