Overcharged my Account

Vodacom over debited my account on the 29 of February. They debited R619 instead of R149. After so many calls to their call center they reversed only R161 to my bank account. Really don't know how they came to that amount. I have been calling them for two months to reverse my money, but they keep on making excuse. Now when I check the current bill for this month is too much as well.