We would like to clarify that your Visa card is connected to your old BG IBAN which is closed now after the migration completion. Please use your new card card connected to your new IE IBAN.
Please also make sure that your card has been activated and that you know your PIN code.
However, note that each new card could be activated through the website mypos.com >> Login >> Merchant accounts >> Cards >> Activate card; or through the mobile app >> Login >> Cards >> click on the + sign at the upper right corner >> Activate new card.
Additionally, note that each card has a unique PIN code which you could request through the account prior to using your card if you happen to forget it.
Log into the mobile app >> go to menu Cards >> you will see a blue screen with a card picture in the middle >> click on the 2nd symbol from left to right - you should see a small PIN sign >> the PIN code will be sent to the connected to the card number.