Bullying & victimisation/harrasment

These guys send a stream of messages even after being called to redress issues they remain arrogant through agents. Vodacom cleared me from a contract I do not know and this guys keep sending me settlement offers. I don't think what they are doing is legal. If I say Vodacom has cleared the impasse, why can't they call Vodacom to clarify than victimise me with their endless sms messages? They are a nuisance