Gave me someone else sim number who owes contract and I get lawyer threats for something I don’t know about my contract is only 2-3 months old

They gave me someone else contract number within 2 months of using my contract sim they say I owe them 5000 on the Vodacom app when I log in it doesn’t allow me access it says it belongs to someone else I get lawyer massage on the sim card when I call to ask they tell me that the massage was meant for the previous owner of the SIM card Vodacom wrack