Bad service and feedback, Again.

I have been with Telkom for almost 6 years now. The last 3 years i have been struggling with them every month. They have been over charging me, charging an amount that just showed up and I never agreed upon. After fighting with them for 2 year regarding that fee, they finally fixed it. Everything has been going well except about 2 or 3 months ago. An outstanding amount just randomly showed up on my invoice. I contacted them regarding this they couldn't give me a legit answer. They told me to send a mail to documents@telkom which i did stating my problem and informing them that i have been paying every month and all of a sudden a random overdue amount is on my invoice. I send them all my proof of payments. They told me that they did infact receive that payment. I asked to be credited because clearly the account department isn't doing their job. Still no credit on my account. Last month I paid them double, which means I alnost don't have to pay them for 2 months, but not according to my invoice!!!!! I want my credit of R339.50. Another problem i recently encountered with Telkom is, last month i called to confirm when my contract is over because I have had enough with them over charging me, not fixing problems and just randomly adding fees to my account., only to receive 3 different dates of when my contract ends. 3 different dates????? I have a copy of my contract with me stating my contract ends this year, only to find out that they don't have the copy I have on their system!!!! How the hell does that even work. Did someone not do their job AGAIN, or did they find out that someone made a huge mistake and just randomly added a new date on my contract, that they probably forgot that I have a copy of the original date, they probably didn't even think about that part. I am DONE with telkom. They are, in fact, one of the cheapest mobile companies, but I will rather go to Vodacom or FNB and pay more than having to deal with this ****ty service and unfairness from Telkom's part. I want my credit and I want my contract end date fixed, not my problem if someone messed up on their side.