Citibank Credit Card Complaint

Citibank Credit card department,

Balance transfer Ohio

I took a $4000.00 balance transfer from Citi Card. This cost me $120.00 for 0 % interest for 15 months. I continues to make my regular charges to my Citi Card. I made my monthly payment, on time, paying off all my purchases and a little additional. I was charged interest because I did not pay off the full balance of my credit card statement which includes the $4000.00 I borrowed at 0 % interest. They charges interest on my purchases even though I paid off my purchases in full and on time.