Incorrect Billing/Bad Customer Service

I logged a query on 14 Feb 2015 and was promised 3 says tuyrn around time to get a response. On the 19th I had not received communication and Icalled again, iI spoke to some senior guy who I assume was the team lead/supervisor of the consultant I spoke to. This guy promised to help me with the query and he promised to touch base on Friday the 20th which he never did. I am sitting almost 2 weeks later with an incorrect bill that has over charged me and no one really seems to be bothered at vodacom, this is one of the worst customer service I have received. I would like this issue resolved before the 26th.