The first thing that you have to understand is that it's a common practice of collection agency lawyers to send those kinds of letters implying that you are being sued when you actually aren't. They play the odds that the letter will scare people in to paying to avoid court judgments.
When that fails and you actually do get sued you are served with a summons and complaint either by private process server or certified mail depending on the local court rules.
Because of court backlogs a 7 day response time is almost unheard of and quite often you have 20 days (or more) to file an answer or appear in court (again, which one of those depends on local court rules).
I suggest you call your local small claims court and see if there is a lawsuit already filed under your name or check the court website if a case search is available.
How much do you owe and when did you default?

