Incorrectly billed and blocked a prepaid line

Vodacom has blocked my lines for March, their reason is due to an overdue account. I’ve called them several times but nothing happens. I eventually email them to get in writing of my query. They billed me for line 2 .. this contract expired end feb but vodacom billed me for March. The payment I made on the 1st March doesn’t reflect. I received an email from vodacom saying ‘ they received my payment but the system hasn’t deducted the payment but yet vodacom sends sms daily that I’m in arrears. The email states that it appears I’m paying less.. with all this info no one does nothing. My phones are blocked even the one line which is no longer on contract is blocked..