Nedbank OTP expires the moment it is sent - and no-,one at Nedbank is concerned to help me. WAKE UP, NEDBANK!

I have several maturing Nedbank investments, over the next few months. I need to give instructions regarding what to do with the maturing funds, but when I log in and give the instructions, the bank sends an OTP, to confirm. All fine, so far - except that the OTP takes a few seconds to arrive, and I'm told the OTP has expired, every time. It expires in less than 30 seconds, it seems (maybe the moment it is sent, even) - definitely not 60 seconds. So, after a dozen attempts, at least, I haven't been able to submit the confirmed instruction. I am in the UK, and don't feel like spending hours on an expensive phone call. I messaged Nedbank, via the App: needless to say, I have had no response. Why must banks make life so difficult for their customers, so often? This is a technology problem, combined with sloppy customer care.