Another method you could look into is from a book, "Toilet
Training in Less than a Day." We used a modified version of this, and our son was completely trained (without accidents) by the time he was 2 1/2.
The book is written by some doctors who were trying to develop a method to train adult handicapped people. It worked so well with the handicapped, they modified it for children. It was written in the 70s, and shows, but it has good ideas that can be modified for today. If you go to Amazon, you can find the book, and read lots of reviews. They give a pretty acurate picture of the book. As with any method, it will work great for some and not at all for others.
The first time we set aside a day, my husband spent about 4 or 5 hours with him, and he basically said he didn't care about using the potty, so we put it off for about two months, and tried again. That time, all I had to do was put him in undies, remind him to use the potty, and praise him a lot. There were a few accidents the first few days, but I could count on one hand the number of accidents he has had since then (almost a year ago). BMs were a little more difficult, but we overcame that within a couple weeks.