Overcharging for MegaBytes not received

In April 2014 I opened a new cellphone contract at Autopage. R470 for 75min, 200sms, 200MB data, AND 500MB promotional data from Autopage PER MONTH FOR 24 MONTHS FREE. In May 2014 I did not receive the promotional 500MB data, so I went to spoke to Joseph to sort it out. He said that it had then be sorted out and that was true because since June I received the total amount of 700MB. In December 2014 I noticed that the debit orders from Autopage subtracted ridiculous amounts such as R957.51 for May, R736.05 for August, R673.09 for September, R668.04 for October, R759.88 for November and R663.45 for December!! This is absolutely RIDICULOUS! So early in January 2015 I went to Autopage Menlyn again, and I spoke to Jean about all of this. He said that there is an extra order for Megabytes on my contract that deducts R144 each month on top of the R470. That is TOTALLY wrong, because I have never asked for extra Megabytes, and besides that I have NEVER received any extra Megabytes for that R144. Now for February I am only allowed 75min, 200sms, and ONLY 200MB. What happened to my 500MB promotional data??? Altech Autopage is *****ING my money! They owe me about R1671.65 at this moment!