Unionized Contracting

I had a few missing roof shingles in the summer and Corey's crew was in the neighbourhood and they did a good job and replaced the missing shingles.

In January, the weather warmed up and when the snow melted, I noticed there were missing shingles on the side and back of my house. I called Corey and he agreed to repair for a set fee. He came when only my wife was home to perform the repair. I have two issues with the work performed:
1) He only fixed the shingles missing from the back part of the house and completely ignored the missing shingles on the side of the house. It was raining when they finished so my wife did not notice until I came home. I called and left messages several times to ask Corey to complete the work and have yet to hear back;
2) He charged an extra $200 for materials to replace a pipe flange (which was apparently fine in the summer) and extra shingles. He did the "extra" work without asking to make sure we were ok with the price. He also said he would send pictures to show what was done but we have yet to receive.

Overall, all I really want is for Unionized Contracting to keep their end of the agreement and fix all the missing shingles so I can make it through the winter, at which time I will likely need to replace the shingles on the entire roof which I was considering to give the work to them but now have changed my mind. Corey, I am happy to discuss in case there is a reason for the above but you need to return your calls in order to figure out next steps.
Thanks