Telkom says I owe them even when I don’t have a contract with them

I would like to raise my concern wrt TELKOM according to them I owe them R2780.00 regarding a cellphone contract I got with them and even handed me over to the *****’s call Nubebt. The last time I was having a contract with TELKOM was 4 Years ago but the billing is for recent months. Everyday I get threatening emails to pay up or legal action will be taken against me even though I don’t have a contract with them. Telkom ***