That debt collector letter is very serious, it should give you the right to dispute the debt. You should then send the debt collector a validation letter. You have 30 days to send the validation letter. Once you send the validation letter, they must prove you owe the debt. A lot of times, they don’t have the right to collect from you, and you may not owe the debt. By sending the letter, it is now illegal, under the FDCPA, for them to contact you again.