Blocking Data Purchase

My Cell Contract with Vodacom Expired 1 Dec 2015. End Nov I gave 30 days notice (as required) that I will not be renewing my contract, but will continue on Pre Paid with Vodacom. On 22 Dec I tried to purchase a data bundle, only to find I was not able to. I just got a cryptic error message. I called the call centre and was told there is a technical problem on the Vodacom system, but that there technicians were working on the problem. I tried again a number of times to load data, to no avail. I emailed Vodacom and contacted the call centre again, Only to be given the same explanation. I aske the consultant if she could load the data on my behalf. After consulting with her supervisor, she said she had loaded the data I requested. The cost for the data would be added to my final bill. About 10 minutes later she called me & told me she told me that because I was migrating to prepaid the \system"has locked me out. The only way I could be unblocked is if I continue on my contract. I find this unacceptable & *********. I cannot use my full service that I pay for. Looks like they are trying to \""persuade/force\"" me to take out another contract. Very unprofessional & disappointing :-( """