Vodacom - greedy, expensive and data expires

Greed runs very high with this company. I have three of the exact same contracts, one for me, one for my son, one for my daughter. The exact same price plan with same airtime and data and monthly fee. Yet, when I need to top up with data, all three of us have different "specials" and different data prices on the Vodapay app. Also, I feel ****** that once I purchase data, that this data expires within 30 days. I paid for it, why must it expire? Checkers does not come to my house to take back the groceries I bought from them if I didnt use the groceries within 30 days, why must Vodacom take back or let data expire? Why is the specials on the Vodapay app not the same for everyone? Due to this , I will now be cancelling all three my Vodacom contracts