1. Who paid for the concrete?
2. Is there a written agreement anywhere as to what the scope of work would be?
I doubt they're an authority on the subject matter at hand.
Find a reputable contractor in the area and get a quote to fix it prior to paying the other guy.
The Contractor paid for the concrete but I paid the contractor. I am almost paid up in full which is a long story from last year to try and get it down before first frost but mother nature had a different plan..... I have a well respected surface prep company to come out for a quote and would have them do it vs the current contractor but as I stated earlier im not going to do it on a slab thats not worth it. It was watered the first day it was down which was wednesday and has rained a bit on saturday, over an inch on sunday and today we are up to another half an inch so it has been getting and staying a little wet except thurs-Sat afternoon. in the contract it stated "the work preformed will be high quality and done in conformity with state and local building codes" This obviously did not happen......

