Mtn Summer Mobile - Pathetic Service

Early last year (February / March 2018) I received a call from Mtn Summer Mobile requesting me to upgrade my Mtn line with them. Realising that this will save me time to walk into one of their shops, I agreed. An upgrade was successfully completed, and I currently enjoy all the benefits of that contract excluding one, the promised cell (handset) has to this day not been received. After a number of unsuccessful follow ups, I then decided to engage this platform. And I am paying for all this service without fail each month, wonder what would happen if I defaulted on my contract. Thank you