Horrible service

I joined amazing vouchers a few months ago. But it's not really worth it. I tried to cancel my subscription and was told by a call center agent that I must pay 4 months of my subscription fee which I was not told when I joined. I then requested documentation to that says I must pay the 4 months and the call center agent then put down the phone. I also emailed them and have not had a response other than saying I must call the call center.