Undelivered Phone Upgrade & No Joy from Customer Service

I was originally an Autopage customer (with no bad service in all the years that I was with them) but they changed to Glocell. Ever since my cell phone bill has been between R700 and R1000 per month, compared to R300 to R400. I then upgraded on 15.12.2018 and was promised delivery within 2-4 weeks. During the 4th week I spoke to a consultant who said that the phone was with the courier. A week later it had not been delivered. When I phoned they said that there was no stock, and whoever I spoke to was mistaken. I am still waiting for my phone!!! Whenever I phone to enquire, they put me on hold, and just don't come back on the line. These people are ******** us!!!! Are we just at their mercy, or can something be done?