SLA not met, no feedback received.

I logged a dispute on the 15 Aug, I was told it would take up to 20 business days to have my query resolved. Its been 20 business days and I still have not received feedback. The call center lines rings continuously for over 20 mins then they cut the call. I have been sending follow up emails but no response. No answer at switchboard either. It's really frustrating when you are waiting to apply for credit and have an open dispute.