Product: Credit card or prepaid card

XX/XX/XXXX I took a trip on XXXX from XXXX, California to XXXX, Nebraska. I purchased my ticket on line and when I was going to pay for the ticket with an existing credit card, I received a pop-up on the screen that advised that if I would apply for a new XXXX Mastercard, I would receive {$100.00} off the price of the ticket. That is all the pop-up offer said. That sounded like a bargain so I applied for the credit card and paid for the ticket on the new card which was to be sent to me by mail. Unfortunately when the bill came for the new credit card they did not deduct the {$100.00} from the total bill of {$190.00}. I contacted Bank of America, the entity which issued the new card and advised customer service of the problem. The agent with whom I spoke said she would investigate the issue and get back to me on my cell phone number which I gave her or by email the address of which I also gave her. 
I did not hear from Bank of America again until the next bill was issued for the incorrect amount of {$190.00} plus a late charge. 
I again called Bank of America customer service and was advised, again, that the issue would be investigated and that they would get back to me by telephone or email. Again there was no further word from B of A. until the next bill was issued with additional late charges and interest charges. The above scenario continued with me telephoning Bank of America customer service by telephone and never hearing back from them until I received a nasty letter from them saying they needed to hear from me by XX/XX/XXXX. Since I was having no success in contacting them by phone I decided to go to the local Bank of America office at which we had been doing business for over 40 years. I went to the XXXX XXXX Branch of B of A and a pleasant person listened to my story and said she would put me in touch with an appropriate B of A person and had me talk to an agent named XXXX, who advised me she could do nothing about the issue. When I asked to speak to her superior, I was transferred to a person named XXXX. XXXX was very understanding and said she would investigate the issue and get back to me by telephone. Her promise seemed similar to about 10 promises I had been given by B of A agents with no follow up. I told XXXX I would be unavailable for and extended period because of a vacation my wife and I would be leaving on Saturday, XX/XX/XXXX. When she did not get back to me I did what I felt was the only reasonable thing and that was to write a letter to Bank of America, explain the situation and enclose my check for the correct amount owed. I then hand delivered the letter and check to the local B of A office XX/XX/XXXX giving the letter to XXXX the agent I had previously talked with about the problem. 
Bank of America has returned my letter and my check with only and unsigned letter stating that to qualify for the credit I had to spend at least {$1000.00} on the credit card within 90 days. 
The only condition for me to receive the {$100.00} credit in the pop-up ad, the offer of which I accepted, was that I apply for the card. It appears that B of A is now attempting to apply a condition which I would never have agreed to had it been on the pop-up ad. I expect them to live up to that original agreement to give me the {$100.00} credit if I applied for the card. I have tendered payment for that which I owe. I expect them to accept that payment and eliminate all the interest and late charges they seek to impose.