Poor service

Vodacom continues to disappoint me, in April i logged a billing query there was about R590 or so that they could not explain where its coming from, the ticket was closed with a comment that my account will be credited, last week i received my statement and to my surprise the R591 amount is there and i just called to find out about this amount , the consultant said he will investigate another service request ticket was logged with ref no . This is ridiculous shame