Over debiting

This is the 3rd and hopefully the final time I write a compalint about telkom mobile , these guys are a bunch of ***** and they have *********** staff to attend to queries , for the past 3 to 4 months I've been trying to get telkom mobile to pay back the money they over debited from me but I've been getting different stories like the matter is at the billing department , we can't find your case number on the system , the money has been paid back , we didnt have your account details etc , today I was told my case is sitting with someone and they \will"start working on it this week "