people are using my address to run up depts

[sisters]

I have had three different people use my address to get loans and goods from cataloges. I have even had someone from provadent knocking on my door claiming that they have collected money from my house for a loan that a man had taken out. I cant see how as i live on my own with my two children and have done for 11yrs. What i want to know is, is there a number or address i can call or write to , to put a stop to this.