Harassment

I am receiving calls from these people on a daily basis and when I miss the calls, I get up to 5 calls in a row there after. I have spoken to numerous agents and asked them to please stop calling me because I am not interested in the product they are selling. And for some reason beyond my comprehension I am still receiving these annoying calls in my working hours! Are they so desperate to sell me a product that I do not need?! Is the aim of selling something not to suit the client's need? ! Well I do not need or want the product.