Call to collect debt but I am not their customer

Nextel has been calling my phone for a year leaving messages about someone else's account. It seems that the person they are looking for has a balance that needs to be paid but the phone number they have on file for that person is wrong. I am not that person!

I tried to return the calls using the number on my caller ID but got some car dealership. The owner complained that I am not the first person who calls and complains, and he said they are not making these calls.

I also tried calling Nextel but they said they can't help me because I don't have the account number in question. It all looks like a big scam to me!