Citibank Credit Card Complaint

Citibank Credit card department,

Delinquent account New York

I received the best buy credit card with zero interest for 24 months. I paid most of it but did not realize it ended. All of a sudden they add $800.00 to my account. Saying I missed the deadline. I asked how much did I owe. They said - dollars. So they told me they will remove it if I pay the - dollar which I paid immediately. They said this is a one time lifetime courtesy. They said 2 billing cycles to apply. Today I call up and I am told that I have to pay. No one informed me and I saw the whole card of what I owe is the extra interest. I asked why. They said the request was rejected to remove the - dollars. So I asked why did they tell me it was a one time occurrence and have me pay - dollars if they were not going to do it? They just refused. I think it is unfair. I think I was misled and basically told to bad you have to pay. I just feel I did n't pay - dollars and they charge me - is horrible. so I feel mislead.