Product: Credit card

I applied Discover Cash credit card XX/XX/2015. I started to use the card roughly on XX/XX/XXXX until XX/XX/XXXX. 
On XX/XX/2015, after online chat with a representative of Discover, I transferred some money to the Discover card so that I had more money to spend other than my credit line. To be clear, I paid off my balance on time so I had total credit line. 
On XX/XX/2015, I was going to purchase an item in a XXXX XXXX XXXX. The amount I was going to spend was within my permitted credit line. The credit card did n't go through. I received a message and an email from Discover requesting me to verify the transaction, which I did. However, I still could n't use the card even after I verified the transaction. Then I called Discover. In next TWO hours, I had been kicking back and forth from the Security department and the Billing department. The security department said with very disrespectful attitude : " The security hold has been cleared in your account. I do n't see any problem. You either let me transfer you to billing department or you have to try another day. There is nothing I can do about it ''. By that time, it had been TWO hours, I was exhausted so I gave it up. 
Two days later ( XX/XX/XXXX ), I called Discover to see if the card is available to use. One of the representatives said there was no problem. To confirm, I called the security department. The lady asked me a couple of security questions. I provided my card number, the XXXX security number of the card, my SSN, my name, my mother 's maiden name, and in what state I got my social security. I answered every question. All of a sudden, the lady said : " I can not talk to you anymore, your card is under review now '' I asked " why '', she said because there was XXXX question I answered wrong and refused to talk to me further and said " if I tell you which question you answered wrong, you would be able to look for the right answer ''. 
Several days later, Discover send me an email saying that they need to talk to me so I called them. The same thing happened. When they asked me " in what state you were issued the SSN '', I asked my husband to confirm my answer because last time, I was told that one of my answers was wrong. They asked me very rudely '' who are you talking to? ". I explained that I have moved XXXX states last year so I just want to get a confirmed answer from my husband. After I answered that question, I was told I was wrong and put my account under review once again. 
Here are the complaints I have : ( 1 ) Discover has been advertising that they will provide certain double cash back to the customer who enrolled their Cash credit reward program, which is the only reason I applied its credit card. Among the cash back that Discover promises, the purchase in department stores will be rewarded one of the highest cash back. I noticed that many people can not use Discover card in those department stores. I was stopped from using the card for no reason. 
( 2 ) They have been very inconsistent and waisting my time. When I first call Discover, the customer service from the billing department said the negative balance was because I had overdrawn above my credit line. I had to explain to them that the negative balance was the money I transferred to my Discover account, and means Discover owe me money. And Discover credit card would not allow me to overdraw. 
( 3 ) They refuse to talk to me to solve the issue. I do n't think I put the security question like " in what state my SSN got issued ''. And I do think my answer is correct. Even if I missed this one single question, I answered other questions correctly. There got to be some way to resolve it instead of putting me under review again and again without any point. I ca n't help thinking they want to stop my account activity until the double cash back policy expires.