Can I top up with a currency that my card is not denominated in?
No, you can only top up EUR cards with EUR and GBP with GBP.
If you attempt to top up your account with a different currency, the transaction will be rejected and should bounce back into the account you sent it from shortly.
You can always top up your card by selling crypto on our decentralised exchange, the PlutusDEX. Here's our guide on how to get started.