Well I had many problems with my son and 1 mos before he turned 3 I took his pull ups away during the day. My son did not like this. he was in tears wanting his pullups. I let him wear them at night and when we went out. Many people told me about this so they actually feel what they are doing. At first he will still have alot of accidents but with my son I simply potty him on a reg basis setting the timer so he even knew when it went off it was time to try. If he had accidents I simply rushed him to the potty had him sit as long as he would tolerate and tell him this is where we go potty not in our underware. It get old saying it over and over in a calm manner.
Within 2 weeks he started going on a regular basis sometimes independantly , sometimes I had to remind him, and he still had some accidents but it was a drastic improvement in 1 month because I struggled so bad trying to train him!
Once he started going regularly is when I started a potty chart where everytime he went we put stickers on it. He thought this was a blast! When it was filled up we would then get him a sm toy.
The underware and the potty chart thing helped tremendensly. So thats what helped us. Good luck. I know its a struggle.
A.