Balance inquiry

I've been a customer since 2023 and everything was fine , The past weekend I tried to use my account to make purchase but when I log in to my app its show I don't have available balance is 0 . I don't understand how coz I just paid Friday and there was avail credit . I sent an email but there's no response I even called the number is n/a How is your customer service operating . Your response will be appreciated . Thank u