Can't get OTP sent to my cellphone

[quintusr]

no i do not get otp, number is correct

[Thulaz]

I have not changed my contact details that I used when I opened accounts with Standard Bank. However, when I try to make online purchases I can't get OTP sent to my cellphone or email address and the error message I get says that these contact details are not registered with Standard Bank. I don't know why is that the case but I still get e-mails, statements etc from Standard Bank on the same contact details. Please explain to me why is this the case. Note: previously I could do these purchase but all of a sudden I can't.