VODACOM REWARDS R720 PRE-PAID CUSTOMERS BUT NOT R 12 000 DATA CUSTOMERS

I have had a data package from Vodacom for the last (almost) 12 months and will eventually spend R 12 000 minimum with Vodacom. I, however, do not qualify for Vodabucks (Vodacom's reward program) benefits. Pre-paid customers spending R29 per month, however, do qualify ... Someone, please explain to me ... THE STORY: Using my data/wifi, I saw that I could buy discounted pre-paid electricity via the Vodacom app. Always weary of ****s and problems, I only bought R 50's worth of electricity for a start. After waiting for my pin for almost 4 hours, I phoned Vodacom. As usual, I was sent from department to department. The only number I was not given, was that of Eskom themselves. Long story short, this is the result I came to (seeing that Vodacom Call Centre staff couldn't explain it to me). Although I have a data line (worth a minimum of R12k) with Vodacom, I can only have the Vodabucks benefits if I have a Vodacom voice & sms line as well. My voice line is with Cell C - still the cheapest voice plans in SA. Problem is that while I made the purchase on the Vodacom app, I was not warned or stopped when I entered my 084 Cell C number. Of course. the app took my R50 immediately. I do not mind losing the R39 (discounted from R50), as they have no means of refunding me. The real question is that of fairness. Surely I (R500/m) am worth at least the same the pre-paid customer (R29/m). How do I benefit from Vodabucks? Must I take another contract with Vodacom. All of this makes no sense!