incorrectly billed

I upgraded in early February.all good but at the end of the February they billed me for admin fee.I was told if you to it online or over the telephone there is no such thing.they even sended me the wrong simcard and I had to go buy a new one.I sended the receipt to them and the said they will refund me but that still did not happen.now the query of the admin bill they cant answer.I spoke to upgrade department where the complaint was lodged and they kept in contact and said it is finalised and I must contact them.I did so and they said I must talk to admin department because they cant help me.I talked with admin department and they said I must talk to upgrade department since cant help me.who the hell must I talked to.