Can't access profile. System still has old cell nr

Hi, I have tried to call your call centre, and I have tried to resolve this, but I can't. I'm trying to log in to my account, and as soon as I'm logged in, it says that I need to enter a one time pin, on a very old cell number that you have. My cell number has changed long ago, so I can't access my credit profile because I don't have that cell number any longer. On the call centre it also does not offer me the option of chatting to someone or the option of replacing my cell number. Can you please assist.