Harassed and Intimidated for refusing to pay a disputed ********** purchase

I was the victim of a ********** purchase on my account. I initially received an SMS asking to confirm if i had purchased anything. I obviously responded with a NO! For the next five days i struggled to get hold of the ***** department... i kept getting numbers that don't work, store and call centre staff that don't know what to do or who to call... I finally got hold of someone and was then told to send documents... I did that, then came the constant harassment and SMS ************... Yoh these people call the whole day and funny enough they always say we can see the ***** dispute just wanted to know how much and when im going to pay....