If I don't pay no service But they don't have to own up to their part of the agreement.

When I sign a contract with Mtn I'm saying I will keep to the stipulations set out inside. However this doesn't bode same for Mtn The agreement set out was for a Huawei P40 Lite a G2 watch and Bluetooth earphones. It has been 4months since I upgraded my contract yet I still haven't received my earphones. Which the store assured me would be a short wait. I've visited the store numerous times I've reported it in a previous post on hellopeter and to date nothing has happened not even a reply from Mtn. Now if it was me defaulting on payment I would have had my service suspended from the word go. How is this fair that THEY can make me wait for service but I have to pay diligently or get blocked from using their service?