wow, that's horrible. I would find a new trainer. I am not a big fan of that rough idea of "breaking" a horse. I don't like to force them to deal with anything. And if the horse isn't even started under saddle, you definitely do not need to worry about flexing at the poll. Besides, flexing at the poll should be something that comes naturally, not forced. With young horses, I do a lot of work on the lunge line. First just teach them to free lunge in a round pen, work up to lunging with a bit and surcingle, then introduce side reins SLOWLY (and at the longest length first) to start your horse rounding. But I would only work on rounding and collection work once you have a very solid groundwork base, and your horse is used to wearing tack and equipment. Take things very slow, or you will be tramatizing your horse. A tramatized horse will never be a reliable mount. Training should NEVER be excessively dangerous for you or the horse. You might do some reading on horse training, I love to read all the different trainer's perspectives. I have a 5 year old I started at 4, and a 3 year old I am already using as a trail mount. This natural, gentle horsemanship stuff really works. My horses are happy, safe and well behaved. Here are some of my favorites:
I really like anything by John Lyons and Monty Roberts, both have very effective training styles. I would recommend exposing yourself to different ideas on training from every type of trainer, and decide what you are most comfortable with. Definitely don't let a single trainer tell you exactly horse you are supposed to do things, especially if it seems dangerous.
The basest horn of his hoof is more musical than the pipe of Hermes.
He's of the color of the nutmeg and of the heart of the ginger.
His neigh is like the bidding of a monarch,
And his countenance enforces homage.
- William Shakespeare