I agree with everyone here.
What kind of "training collar" does your trainer use?
I use a no pull harness on Leia & Han. Works great. The leash clips to the front of the chest on not on top of their back so they don't pull. Clipping to their backs tends to make them want to pull more.
Never use a trainer or training methods on your dog that your not comfortable with. Anyone can call themselves a trainer, there is no real qualifications for it. We have learnt that the hard way and the expensive way
gone to many useless and costly trainers that did not work and perhaps even made things worst for us.