My account Debited On Air denied payment

I was contacted by this company so called On Air TV the consultant introduced himself as part of Multichoice .I trusted them and purchased the decoder Xplorer .The problem started when I switched banks .I don't know what happened from On Air TV side my account gets debited every Month on the 27th but I receive calls from different agents saying my payment was declined from their side .I once asked them to email me the settlement in order to avoid for my name being taken to bad record that never happened .I'm sick and tired on this Company so called On Air TV .