Unable to use online banking

I am currently in the UK and I am using online banking to transfer money and pay bills in SA. I have spent the last 4 weeks trying to change my OTP delivery method from cell phone to email so that I could use online banking in the UK. However when the method was changed it caused my internet banking to stop working. I rang the call centre and nobody could help and I just got given a reference number. I rang everyday for the past 4 days and nobody at the call centre was of any help. the last call resulted in telling someone telling me it may be another 7 days before I get a reply on the issue. This is completely unacceptable as I am now in arrears on bills. Apparently there is absolutely no other way to conduct banking whilst in the country. The last 4 weeks have been extremely stressful and is just a continuation of a very poor experience with Standard Bank. I hope someone who can help reads this and gets in contact with me.