Telkom *** Harrasment

I have been called morning , day and night by *** number from Telkom trying to sell me a contract I can afford. I have tried to explain I cant afford it and I have 4 contracts already with telkom( with poor coverage) but they insist and they are rude( surprisingly they all of Indian descent) Please tell them to stop or I will have to cancel the 4 contracts I have already and ask them to show some respect