Spend all of the money you want on a Vet and a trainer. But you already answered your own question.
My horse kicks with his back legs every time he is ask to do something,he does not like, he is scared off. He stops and kicks.
You already said he does it when he does not want to do something or go somewhere.
You said you did not let him get by with it, What are you doing now to "not let him get by with it"?
You can 'correct' him each time and will will gradually do it less and less until it comes to something that he REALLY does not want to do.
OR, you can get after him hard and break him of the habit completely. If it were my horse, I would take the long ends of a pair of heavy harness leather western reins and I would spank him really hard in an 'over and under' manner. I use the 'over and under' spanking so a horse does not learn to duck and dodge and 'spin around' from a smack on one side. That is a good way to trade one bad habit for a worse one -- ducking around and facing home or the barn. The 'over and under' spanks both sides in quick succession and the horse has no where to go but forward. The 'hard spanking' serves as a deterrent and you only have to do it once or twice and it is all over. The behavior is gone. The 'tap' or 'light swat' just turns into nagging and a horse that 'barely' quits each time but keeps trying to do the bad behavior. This turns into worse behavior with a lot of horses and the constant 'pecking' fight is on.
After you accomplish your goal of going forward without hesitation, you need to take the ends of the reins and swing them around so you 'desensitize' him to them and he know it was his bad behavior and not the reins that caused the spanking he got.
You will find that after a good spanking, this horse will get a lot happier and more willing to do everything. It is a 'positive' all the way around.