Citibank Credit Card Complaint

Citibank Credit card department,

APR or interest rate California

recently i talk to best buy credit card about the interest charge.almost - dollars where from they say first i have a late charge i said i talk to your customer respentive they say will take care for me i say i pay full amount for last - statment why i have interest charge they said because the billing cycle i say every credit card i pay only pay for stament amount not worry about your billing cycle i ask them to to take care they refuse to take care you need to pay for billing cycle interest i feel that they are not honest to customer they are cheating.