What to do with a contractor that has not completed the job?

Hired a licensed contractor to do stamped concrete driveway, walkway to patio, patio, paver walkway to front door, paver wall around patio and waterfall. The concrete color turned out lighter than expected, so he was asked to stain it (we had to buy stain). Paver walkway was laid down but not finished, i.e. no retaining wall, polymeric sand, etc. Basically the job is at 75% complete, we started staining concrete on our own, because we want to get it done at this point. The contract we signed with him is 90% paid for. He has been calling us to say that he will come out in 2 days, 3 days, and so on, I'm guessing he's buying time. Not sure which direction I should be going with this situation.