Vodacom ****** me my data

I am currently in a 24 months 500mb data and R175 air time contract with Vodacom. Have this contract since 2016 and has been renewed 2018 may. Initially I used to pay R125 for R150 air time and 500 Mb, hence now I am paying R153 for R175 air time and 500 Mb. The problem is that they have this tendency of not allocating my data and once they start not to allocate them it becomes a monthly normality, where I have to call them every month. This thing started before I could renew the contract in 2018 then it started again last month. I called them and the told me stories but at the end they told me that they had a technical problem and they gave me R89 air time and promised me to resolve the problem. This month they did the same but when I call they saying they have line up of calls I should hold for a while but it seems I have been holding for ever. I don't have a problem with the money I am paying for now, I want my data to be allocated as an yesterday.