Constant phoning- Promotional gift harassment

Every week you receive a call stating that someone else gave your number up for a promotional gift. Although you ask them several times not to phone you, they call you again the following week giving another name that nominated you. The agents phoning don't listen either, because you tell them that you are at work and cannot talk and then they tell you that it will not be a long call. Absolutely irritating. Keep your gifts and stop harassing people!