Markham Masonry Ltd

HOMEOWNERS PLEASE BEWARE.
I hired and paid this contractor to replace my front walkway and retaining wall - he is now unreachable.
Markham Masonry & Contracting
I have been calling Markham Masonry & Contracting everyday for over a month now and am at a complete loss as to why the owner is ignoring my calls. I have been a good client of his in the past, I hired him previously for 2 jobs (parging my basement and rebuilding my chimney) before having him pour a new walkway at my home April 2016 - I paid him the agreed upon amounts in a timely fashion i.e. some up front for supplies and the remainder when the job was completed.
The walkway was poured and not even a week later there were 2 cracks across the walkway and 4 in the retaining wall. I called him right away and he came out and agreed that it should not have happened and he would take care of it. He pushed it back all summer and we ended up agreeing in the fall we would leave it for the winter and he would fix it in the spring of 2017.
He came out 2 times to my address this year (2017) already to look at the cracks in the walkway and retaining wall - agreeing again that it needed to be fixed. That he would fix it and "make it right". He had a plan for the repairs.
Additionally, he left worksite debris (chunks of old concrete from the previous walkway and dirt) for me to clean up - which he agreed to take care of when he returned to fix the cracks.
At this point I have to assume that he has no intention of completing this job as he has not responded to any of my calls and in the past he had always responded promptly. The unfortunate part of this is all the agreements were verbal. I had never had a problem with him in the past so I didn't think it was needed.
I can't find an address for him and his website goes to a yellow pages page. His email is out of service as well. I can't find any information on him on the net which seems incredibly odd.
I can't express how upsetting this is.