bill payment

Hello, in December I purchased a plan for 2 SIM cards that are data only and paid at the end of each month.  In February we had to leave Portugal in a hurry and I closed one account and was able to pay the monthly bill online through the NOS app. For the second on I went to the local shop and they arranged to close the account 2 days after I left. I have returned home and I received a message to pay the balance on the second account. I tried to logon through the NOS app but I can no longer do that because the accounts are closed. When I entire the mobile # I was assigned the response is it doesn’t exist. How do I pay the balance ?