Contract Phone

Mtn really disappointed me I had a contract with them this year February I closed my account paid off everything after a month they sent me a bill saying I overpayed I called them they confirmed that...they said they are going to refund me

They have been playing hide and seek with my money I gave three assistant my proof of account until today they telling me no one has done anything they just ask for my details and then they do absolutely nothing...I'm still waiting for my Refund MTN.