Not stop harassment

Last year I purchased the mink blanket combo from Homechoice. I was very impressed with the service I received. After my first debit order went off not once or twice, but three times, I started getting disgusted with the service. Then came the marketing calls. I told them I am not interested in buying until my current account is paid off. Only then I will consider buying. They keep on phoning every day and every time they promise me they will make a note on my profile not to phone me. But tomorrow comes and another consultant phones me. What must I do for them to stop phoning me. To be honest, I am not even going to buy anything again from them. Will rather buy directly from the bedding shops.