Euro Invoice on sage

I have a client who has Sage 50 Professional 2012;  they have set up a new customer, with a Euro currency.  They only have a sterling bank account, and have been paid therefore in sterling.  When I try to allocate the invoice receipt to the customer within the bank module, it won't let me as the customer is set up in a different currency to the bank account.

All I see I can do is set the customer up as a sterling customer and print an invoice that only shows the euro conversion...........  any better suggestions?