Waiting two months for delivery of a handset

I am currently waiting for a delivery of my handset after I upgraded my contract on 7 August 2017. I was informed by the courier company that the package was returned to the warehouse on 30 August 2017. The warehouse has no contact number and can only be contacted via e-mail. I was informed by Summer Mobile that a return number must be generated first before a delivery will be made. No one is able and/or willing to assist me in providing this return number because the warehouse is not responding to e-mails. MTN call centre supervisors are not able to assist me neither are they willing to put me through to someone in charge to lay a formal complaint. I still have no solution and see no way forward.