Frustrated client

The authentication process of FNB at their customer service is frustrating and bad.i have a cellphone which takes two sim cards. FNB gave me a SIM card recently which I am using on my handset. So now when I phone their customer care, and they send the verification sms on my phone it's not coming through and I am being told that I must phone from a different phono or landline.. Surely FNB can use other options to authenticate their clients, now I am borrow phones or drive to the branch. Really this is absolutely pathetic from a bank that pride..