There are two ways to stop collection calls or letters. One is by sending the debt collector a cease and desist letter. Make sure you are doing the right thing when you do that because if a debt collector receives a cease and desist letter, sometimes having no other choice, they may sue you if you do owe the debt. If you don't owe the debt, a cease and desist letter is the best possibility of getting them to stop. Secondly, a validation letter is your best tool. A validation letter requires that the debt collector prove you owe the debt. If they can't do that, it is illegal for them to contact you again.