Product: Payday loan, title loan, or personal loan

Good Afternoon, I am hoping you can help me with a problem I am having with Citibank. 
In the past, Sears Citibank has sent me checks in the mail that you can cash for 0 % interest. About 2 years ago I bought my rug using one of  these checks. I cashed the check for {$9000.00} to a carpet company and I was billed {$9000.00} which I paid back within the allotted time frame at 0 % interest. 
Everything was great. 
Recently I received these checks again, for 0 % interest for 18 months. 
I called Citibank and asked the representative if I could use this check to pay off my XXXX Home Equity line of credit. She explained that yes, I could do that. I asked her if I would still get the 0 % interest for 18 months and is it okay to write the check to XXXX and not a store. Again, she said yes and suggested I deposit the check into my account, let it clear, then pay XXXX. 
I had asked her multiple times if it was 0 % interest and each time she assured me yes, it was 0 % interest. During the call, no less than 3 times, she said the full amount would be due in XX/XX/XXXX. I had to correct her all 3 times that it was XX/XX/XXXX. She assured me yes it was until XX/XX/XXXX with the 0 % interest. This should have been a red flag to me that I had to correct her so many times that maybe she was not knowledgeable. 
I asked for a credit line increase to {$16000.00} since my current limit was {$9000.00}. 
She put me on hold and came back on the line and said I got approved for {$15000.00}. 
A few days later, I cashed the check for {$15000.00} and put it into my account to let it clear first before paying XXXX. Since then, I have gotten a bill for {$15000.00}. It said on the bill that I went over my credit limit. So, I called Citibank and asked them how can I be over? My credit limit is {$15000.00}. They then explained to me that there is a 5 % interest charge for cashing the check. 
I was never told there were any fees to cash this check. When I had used the first check for the carpet there were no fees so I did not expect a fee this time. We never had discussed a fee. She had assured me repeatedly it was 0 % interest for 18 months. 
I told Citibank that I had asked the representative multiple times if I could use the check in this manner and still get the 0 % interest for 18 months. I went on to say never did she mention a fee of any kind. 
My bill says I went over the credit limit, but when I called they said the fee was from a 5 % charge to cash the check. So, there is some ambiguity as to why I was charged. 
They certainly never told me that I could only cash the check for {$14000.00} to make room for this {$750.00} fee. 
At this point this issue went up to the executive offices and I spoke with XXXX at XXXX. XXXX did offer me a {$100.00} credit which I accepted. But this still leaves me with a {$650.00} fee. 
XXXX told me that the representative had told me twice about the fee. I asked XXXX to play the call so we could both hear it together. She said I can not listed to it unless I get a subpoena. So, at this point I have not heard the call and have to take her word for it. I do not recollect her ever mentioning a fee. If I had, I would not have accepted the money. 
( XXXX XXXX XXXX  offers these checks as well and when I called them they clearly explained that there is a 3 % fee to use their checks. I declined the offer and never took the money because I did not want to pay this fee. ) So, I asked XXXX, when she told me about this fee, what did I say? She said I did not say anything. I asked her if we were both talking at the same time and maybe I didnt hear her but XXXX could not remember. Either way, the representative certainly did not make it clear that there was a fee. 
There was no discussion about the fee nor did I agree to this fee. 
I believe Citibank had a duty and a responsibility to clearly explain that there was fee. 
You know you call some companies and when they are done selling you whatever they are selling the say now mam I have to read you this statement, and you need to agree when they have finished reading. 
Why doesnt Citibank have to read some kind of statement explaining their fee at the end of the call? 
It was this representatives job to fully disclose this information and to be clear and upfront about any fees. 
If she had done so, I would never had taken the money. 
I think since this woman made a mistake that Citibank should void this fee ( and have better training and practices and procedures in place so this kind of thing does not happen again ). 
Is there anything you can do to help me? 
Kindest Regards, XXXX XXXX XXXX Cell XXXX