Citi XXXX XXXX Credit Card - have balance under promotional offer - Titled Offer 5 - 4.99 % until balance paid - had no other balances due. XXXX/XXXX/15, purchased concert tickets. Purchase went to Offer 9 - 1.99 % until XXXX/XXXX/15, then standard rate of 17.99 % after. Concert cancelled by artist. Purchase refunded by Citi on XXXX/XXXX/15. Citi applied refund under Offer XXXX instead of Offer XXXX. Charged Interest on offer XXXX for XXXX and XXXX for a refunded purchase. Statement showed Offer XXXX balance subject to interest rate of {$140.00} with interest charge of {$0.00}. Made payment. XXXX Statement showed Offer XXXX balance subject to interest rate of {$170.00} with interest charge of {$0.00}. How does a balance go up by {$34.00} when a payment was made and the interest charge was only {$0.00}? Also, because payments apply to higher balances first, and Offer XXXX balance is much higher than Offer XXXX, my next payment will not touch Offer XXXX and Offer XXXX will revert to the 17.99 % standard rate. The practice of not applying a refund to the offer in which it was charged has me paying interest on a refunded purchase and has set me up to fail completing Offer XXXX in the required timeframe and raising my interest rate. Because the purchase was relatively small, the net effect is minimal but, if this were a much larger purchase, like if I bought tickets for a large group so we could sit together, I would be subjected to a much higher interest payment, especially after it reverts to the standard interest rate. I feel this practice is fraudulent and wonder how many others are affected. I am sure it could exceed XXXX per month that Citi can collect fraudulently, with most people unaware. I spoke with manager with Citi, but they unsatisfactorily explained this to me. 
