not receiving my free data on going since oct 14

I upgraded my contract in october 2014 and the vodacom smart s package i took for R499 per month included the following as per the brochure I received- 75 anytime minutes per month/ 200 sms's per month/ 200MB data per month and an additional 250MB data per month but since october 2014 I have not since October 2014 received my additional 250MB per month but only get 200MB every month, I have logged a call in december and all they did was add a bundle of R60 extra to my account for 250MB data which they have refunded me for but to date I have not received one call and the problem is still not resolved, I call them every week and speak to someone new and they keep logging a new call to no avail. I would just like to be refunded 750MB data excluding the decmeber data which they refunded me R66.00 and I would like my additional data to be allocated to me every month as per my contract. I'm just not able to get this problem resolved and I do not know who to speak to or how to get my contract fixed but I'm so frustrated and at my wits end with their customer service. Please help me resolve my problem in correcting my contract. Thank you Monique Meyer