Disgusting

I'm frustrated as I can't get thru to customer service. And the mtn shops won't help me. This morning when I punched in my R30 airtime mtn just gave me R10 however it went off by my account as R30. This is not the first time this has happened. Even when I get xtime R10 they only give me R2 the when I load airtime they deducted a whole R11. You really ripping people off and it's disgusting. I'm definitely changing to another network.