First National Bank
SMS received stating that I am in arrears

I receive my debit SMS every month and now fnb wants to tell me that I'm behind on my payments, tried to phone fnb but not getting any response, SMS states that I have to pay R 2392 immediately. Please respond as soon as possible al let me know why I was never informed that my device was behind because as per my smsses I've received everymonth it's up to date