Leak in American Standard single-handle shower valve

My local plumber installed a valve repair kit and invoiced me $300+ parts+labor, and it STILL LEAKS, worse than before!

$85 - diagnose
$85 - pickup ordered part (grrh, ship it to my house..)
$85 - install valve
$75 - repair kit

Now he wants to cut through the wall and replace the whole thing with Moen.
It will cost me at least another $500.

All for a small drip, drip, drip !!

How should I deal with this issue. I just want to pay a fair price for a simple repair!

FRUSTRATED IN VERMONT..

 

I would be tempted to ask for my money back and call another plumber. I don't know if it's just that I'm good or he's bad but I've never seen a leak that I couldn't fix one way or the other unless the fixture/valve is busted/cracked or badly ate up in which case a good inspection would have told me whether or not to order a repair kit/cartridge or whatever...

 

Did he tell you why it was still leaking. I bet he has the wrong parts or has them in wrong. How old is the valve?