Internet banking (IB): no return phone calls

I have used IB for many years while living abroad. For over a week now, RVNs (per sms) are NOT received on my mobile phone. I do receive other sms'es from RSA sources. IB is thus useless. Stuck. Called Absa 4x, each call lasting more than 10 minutes. No solution offered. Wrote over 8 e-mails with full explanations. I made a request for call-back with solution, 4x in about 6 days. No call received.