Ah, I have two of these: true stories.
1. We had a phone number once very close to that of a pizza place. We had lots of calls, but there was one very persistent guy in particular who would call in series, never quite believing we weren't his source of sustenance. Finally, one day when my brother was visiting, this guy called maybe three times in a row. On the fourth call, my brother answered and very politely simply took his order....
He must have called the real number to complain when the delivery didn't arrive, because we never heard back from him.
2. The ultimate wrong number, though in a slightly different sense, was done by old Ma Bell herself. I discovered that my long-distance service had been slammed, from Sprint to AT&T, at an exorbitant price. It took me two full days to get past the denials that AT&T "never" slammed people, to find out what happened. As you may know, AT&T sends out "checks" for $10 or $15; if you cash them, you have agreed to a change in service.
Turns out, AT&T had mailed one of these come-ons to a guy who had had the phone number 2 people and over 3 years before. Naturally, he cashed the check: free money for him.
It took literaly months to get the charges straightened out and off my bill.