Charging me for BIS. DOnt have blackberry

I upgraded more than 18 months ago. Phoned today for early upgrade and was informed that i am paying for BIS. I am not using BIS because i don't have a blackberry. I am using Samsung Galaxy S4 Mini. Was told that they will only refund 3 months. This is ********. I am not checking my account because i trust them. Just shows you that you cannot trust Autopage or the people working there because they are suppose to know this when you upgrade and then cancel the BIS. So now i have to pay for an mistake made by them. NOT ACCEPTABLE. Seems to be okay to overcharge someone and to keep quite about it until someone catch you and then only pay back part of the money they took. Where did this money go? I want it back.