Poor service

im very much disappointed in them, have been ****med. They say i owe them, while i did not purchase anything for the passed 3months. On their statement it says i have used all my buying credit and the purchase of 2646 was made on the 8 june, on the same day another purchase was made of 6899.65 and the card is with me and did not buy anything. So they are now *****ing us