Double- Barrel,
I feel your pain mate.
This is just poor instructional technique. I have flown with plenty of muppets in my private and professional flying career. Obviously, it difficult to challenge people who have much more experience than you, however when safety is compromised you must speak up in a diplomatic way, otherwise accidents will happen.
I loved instructing on light aircraft, and also on jet simulators. On a positive note, flying with clowns like you are describing gives you as an aviator an appreciation of how not to do it and shapes your own development, certainly if you would like to instruct when you have the necessary experience.
Enjoy your flying mate, it is a great past time.
All the best.