Disapointed at Vodacom for the second time.

for the pass fewmonthswas unable to access vodacom due to they new installation. in 14 september 2015 when i manage to get to my account i then realised they incorrectly billed my DATA account, i then queried with them immediately ref: 1-***. what dissapoint me is that my name get affected as a bad payer because if thier incompitancy. they keep saying they will call me back but i never get the call. i followed up on 16/09/2015 and again on 02/10/15 where i was told it sorted they got feedback and a credit will be issued i must check after the 03/10/2015. the lady even explain that i wasnt the only one billed incorrectly due to the new system. on the 07/10/15 when i check it still not sorted when i queried they said account department will call me before 5pm, i did get that call. 08/10/15 i called again and Letisha(apologies if not spelled correct) told there is no credit and the query is pending and i must wait with no time frame while in that matter my credit record gets affected. according to her it could be take over a month. my credit record is very good and i am not ready to have a bad one because of Vodacom. can they please sort out my account.