Munch gave some good advice.  

As for a dealer being "well-known and respected",
that should not be a factor in your actions. 
Sure, many people may say good things about them;
but I'm sure none (or next to none) of them have
had to seek a damage claim like you have.   

Don't worry about being blacklisted-- other cel
dealers will not even care what this "well-known
and respected" cel dealer says about you.  If
someone ever refuses to deal with you, just have a
 different "well-known and respected" cel dealer
send out a letter of recommendation for you.  I
know there are a few that will.

Rather, you have the power to blacklist THEM by
letting us know who they are.  

If you let this seller get away with their
low-life, irresponsible actions, this same thing
is bound to happen again, either to you, or to one
of us.  

Remember, the longer you wait, the more difficult
it will be to resolve things.  If you are still
trying to resolve things with the seller, set a
deadline!  But I'd recommend filing a claim
yourself in whatever way possible--  e-bay claim,
credit card chargeback...