Bad accounts service

Vodacom sent me my statements on 8 August. I noticed that the statement is incorrect. I upgrade to a 20gig WiFi on a certain amount which I signed although Vodacom charged much more. I received an email from them on the 15th August that they will pass a credit for the 2 months which they charged too much. I keep the money in another account t because I will only pay them when the credit notes is through and statement is correct. Absolutely nothing happened and they promised that the credit notes will be through in 48hours.... Is is now about 20days later. Pathetic.... Don't know what is going on in their accounts department. I will not make any payment until this is resolved.