Barclays PLC Credit Card Complaint

Barclays PLC Credit card department,

Advertising and marketing Florida

In -/-/-, I received an UNSOLICITED offer from UPROMISE BY -, for a MASTERCARD. This card is issued by Barclays Bank Delaware, -, Delaware, FDIC. The offer clearly stated that if I used the card for a purchase within the first 30 days, I would receive a $100.00 CASH BACK reward. I did make a purchase, and did pay the UPROMISE MASTERCARD for that purchase. Now, many months later, and after making repeated calls, I still have not received my $100.00 reward. In response to a complaint I made, I did receive a letter from Barclays Bank Delaware, dated -/-/-, acknowledging that I met all of the requirements, and also stated " ... I have confirmed that Upromise has mailed a check to you in the amount of $100.00 and you should be receiving it shortly. '' THEY LIED ; As of this date I have never received a check from them!! Barclays Bank is an FDIC bank. Can you help me?