Double charge for both Leased Fibre and Interim Access not being attended to.

Whats up with Vodacom charging us for both Fibre leased router and interim access. To think that I did not even use the Interim LTE router because on the day Vodacom delivered my fibre router is the same day Vumatel came and installed everything they had to. I should be paying R649 but they are charging me R1317. When I phone the call center they acknowledge their mistake and promise to sort it out but its being 3 months and anything has been done to date to correct that mistake. Moreover I am being taken from pillar to post and all I here is that the service call has been escalated and they are waiting for the manager approve the credit but incorrect invoice are still sent out, incorrect amount is still being debited from my account. When is this going to end or is Vodacom kicking me out...