Did you receive this "certified" or just regular mail? i.e. did you sign anything for it?
If you did not sign anything - they technically have no proof of contacting you.
One option then is to ignore, ignore, hide, and delay, until it goes away.
Assuming you don't go to meetings, do not answer their calls (even better - get a phone that blocks ph #s that u tell it to). Do not sign for any correspondence via mail or commercial carrier that comes from them or an "unknown/unmarked sender".
As for avoiding them in person, you might have to be a bit more pre-cautious than ususal. Can they freely approach your home anytime? Is there a way to prevent that?
Anyway - a lot depends on your situation, but if you've faded and aren't around JWs anymore, it can be a way to turn the tables on them. I think there was one poster that successfully filed a restraining order on the elders ... and I don't believe they ever proceeded with the JC after.