American Dental Service / Fillings kept falling out
I went to American Dental Service in the South-eastern PA area and received terrible treatment. They replaced a ten year old filling that fell out (from another dentist) and then their crappy fillings fell out twice afterwards within two months each time.
I then went to another, private, dentist. The new dentist took his time and also shaved down part of the tooth so there was less pressure on it. My filling has now been officially fixed for a few months now.
The best thing American Dental Service did was refund my $150, though that took persistence and a few months of waiting.