Device not working

I have recently upgraded my tracker device and had it installed sometime in October or November 2018. The last signal the device picked up was on the 22 December 2018. I have queried this in December and was advised that the issue was due to technical issues with MTN and that issue would be resolved that week. Last week when I went online to monitor the movement of my vehicle, it showed that the last signal received was 22 December 2018. I contacted the call centre on the 02/01/2019 at 10:15am and spoke to a gentleman by the name of Terence Nkombe who confirmed that a technician would be sent out to have a look at the device. This has still not happened.