First, thank you to everyone for your support on this. Sometimes I'm out in left field, but when it comes to something like this, having our parents taken advantage of, there is no reason for it.
I spoke with Mom yesterday. The plumber returned to look at the persistent leak from under the tank, same plumber, very nice and clean shaven. He looked at the toilet and said that if there is still a leak, it must be a cracked tank. Standard fee for toilet and installation ~$500, but since she had work done, they would credit half of the $282 for the rebuild and bring it down to ~$350. This time Mom was ready for it and quickly showed him the door. Yeah Mom!!!
Pinkie and I will be driving down for her 71st in July, so Mom gets a new toilet for her birthday; every woman's dream birthday present. Well, and the digital cam she's been wanting too.
So this story ends on a good note. No-one got hurt too badly. I don't think we'll ever get any of the money back. But, we'll get her taken care of in short order.