Nedbank account verification

I have been overseas for 10 months and my registered cell number with the bank is no longer in function. Nedbank is constantly sending me OTP to that number, despite the fact that it does NOT exist anymore. I have to appear in the branch to change the number, which is impossible for me to do. I cannot change the number or have the notifications sent to my e mail, which is registered with the bank when I opened an account. Please assist before I close the account alltogether.