Discover Credit Card Complaint

Discover Credit card department,

Rewards Delaware

Last month I received a new credit card from discover card. They changed the product that I already owned as I was not using my existing card anymore. The new card looked better therefore I activated it. When I checked my account online it showed a negative rewards balance of $120.00. It did n't make sense for me to have a negative balance as I was not using the card much for over an year. When I inquired they did n't give me a an explanation and said they would check and get back to me. I never received a call therefore I called again to check. At that time they said it could be due to returns but since the returns over 2 years did n't even amount to $500.00, it was unlikely to get - $120.00 balance. That theory was rejected and then they said they will get the issue to headquarters and some supervisor would call me in - hrs. Never received a call again. I then sent a message and they replied that a supervisor had left a message on account that it could be due to a transaction that was not paid using discover card. Again it was a theory and they never mentioned the transaction in dispute. Also, how could they offer a reward and then reverse it when the card was n't even used. It did n't even make sense. I again asked for explanation and have n't heard back yet for a week now. I need to know why I have negative balance in rewards and if there is no decent explanation I want the negative balance to be reversed.