Uncontactable people. Worst service. Doesnt get back to me after multiple requests

Okay so these guys have been debiting me non stop every month for more than a year when i know for a fact that i owed them less than what they have took in total so far. I can't call them because you buy R100 airtime and the hold till your airtime is finished. I sent them multiple request to call but they don't. I don't receive a statement and i cant reverse any debits because its a debicheck which i never approved. Can someone call me please for the 100th time that i'm asking. i want to know what is going on.