No response and no hot water after 5 days and counting

I have now been waiting for 5 days, and still do not have a technician/plumber assigned to replace my burst geyser (geyser burst after 3 years - under warranty). The call centre cannot put me through to a manager/senior person. I have offered to pay for my own plumber to replace the geyser. No response. No flexibility. No hot water for 5 days and counting.