Dismal Customer Service

I have closed my account in June but was still debited for both June and July. Have made numerous calls and emailed just to have them call me once and when they didn't get through advise I need to call customer service who doesn't even call you back when your line drops. IVR tells me my profile is verified but the agent tells me no my number isn't verified and if I have a dual SIM I need to take out the SIM card and call again because they cannot assist. I am being inconvenienced when all I want is for my refund to be processed and debit order to be canceled. I wasted so much airtime calling and they don't even have the decency to call you back when your line cuts