Telemarketer is charging me $350! i supposably bought something? what to do? PLEASE HELP!?

i answer the phone at work, its a telemarketer, they tell me about some advertising thing they do for businesses and they never seemed to offer anything they kept on blabbing off and they asked for clearified my work's address and i said my name when i answered, while on the phone i said "ok" to something cus they kept on bugging me. Next week they call and say i purchased something when i never gave them ANY billing info or my cell/home number or my house adress, i told them i didnt want anything to do with that so they cancelled it and now they are charging me a $350 cancellation fee! what!!! but i gave them no billing information so how can they cancel something i "bought" this happened a year ago and now they are calling everyday at work and i just tell them, well i make up a name, and say im not here. Are they legally charging me? i dont want any law suites but is it fine if i keep on ignoring them??? or this serious??