Infuriating Change of Internet Platform and Customer Frustration!!!

Nedbank change their internet banking platform and it appears we have to re-register. As I have a new mobile number and live in the UK now, they sent the OTP to my old number which means I cannot access my account. I have indicated on numerous occasions that my number has changed and get told to come in and change it!!!! How can I do that when I live in the UK?? I have sent emails - no response. It is infuriating and I need to pay my bond and other financial commitments but do not have access to my account .Why on earth do they change a platform and make it so much more difficult for the consumer????