My mother passed away and we had a professional floor installation (supposedly). I went through most of the key points of the installation for the warranty. I did not tell him he needed to measure the width of the room and figure out if the first row needed to be cut lengthwise. We ended up with less than a half inch strip along the wall to maybe an half inch through the kitchen doorway. He glued it in place. I don't know if it's glued to the floor or just the adjacent plank. He apparently told my sister this was fine. I'm concerned that being in a doorway area it won't stay in place. I think he's responsible to fix it even if he has to take out the whole floor. Also he didn't mix the boards properly and there is a large patch of lighter boards in the dining room. What should we do? Is there a way to strip/cut the first row, slide the installation over and insert a wider row where the strip is?
You have learned the hard way to get references, and phone them. You could probably take them to small claims court and win, but it would likely be more trouble than it's worth. Short of that you can try:
Put your complaint in writing, with photographs. Go see him, and say that you want this made right, at no additional charge. Vinyl flooring locks easily enough that he should be able to relay the floor fairly quickly.
If you don't get satisfaction that way, put a complaint in with the BBB.
Note: There are dinks out there who, when called out on a bad job, will make sure that there are going to be further problems with the job later.
I am not a lawyer. The advice above is worth what you paid for it. Maybe less.
Normal practice at a doorway is to put down a transition strip. This is a piece of moulding with a cross section of a short very wide T for equal heights transition, or a ramp down one side for floors of different heights. The transition overlaps the floating floor and allows it to move.
Plank flooring is easy enough to do, and from your question you know something about it, you may find it easier to buy one more box, take up the floor and redo it yourself.