Sim card cloned and charges on account not mine

I took out a contract with Vodacom about a year and a half ago, i only used the cellphone, i destroyed the sim card as there was no use for me to use it, a month ago i received a bill from Vodacom for 1.5k which was strange becasue for the life of the contract i have never used this sim card. I contacted Vodacom to notify them that my line or sim was cloned and can they please investigate. i then received a call no less than 24 hours with no evidence or support, i get told by Vodacaom that i am liable for the charges as the account is on my name. I then told the consulatant thats not good enough as this is ***** how can i pay for something i didnt use. She was extreamly rude with me. What customer service is this???? i refuse to settle the account it has nothing to do with me. thwy need to do their homework properly.