Vodacom not honoring their contract deals

I am very disappointed in Vodacom. I have taken out a data contract with Vodacom of 50gig any time and 50gig top up plus a 50gig night owl. total 150 gigs. For the past three months I have only received half of the day time data. I have complained to their customer call centre on a number of times, I have even went to Midrand to Vodaworld to try and sort out this problem and still nobody can help, they just escalating the problem to the next department. I really do not have any joy what so ever from Vodacom