Hey, GJN_mqxi.!
Sorry to hear about your payment issues. Do you have the game on Steam or Uplay. If it is Steam please make sure the Steam Overlay is enabled, you can find how to do this here:
Open the Steam client and navigate to the Steam > Settings/Preferences > In-game tab. ...
Right-click the game in your Library > Select Properties > Under the General tab, check the box next to Enable the Steam Overlay while in-game.
The default shortcut is Shift + Tab.
If it is Uplay, please close any anti-virus or pop up blockers temporarily and test to see if it works.
Please let us know how you get on, thank you.