How sad is Vodacom service

I tried to ask them about their math If a 1GB is R 99 and a 3 GB is R 229 ( no 2 GB listed) The average is R R 152 for 2 GB. So when they say that you receive a 25% discount on the 2 GB @ R 131 how can that be when 2 GB is R 152 X -25%= R 114. So what do they do? They put me to 4 different departments that say it's not their department. I guess you get what you pay for when it comes to a job at Vodacom. Quite sad.