Diann, I know how you feel. Sampson who has a gorgeous thick shiny coat and who is a wonderful, sweet cat turns into a little :censor::censor::censor::censor::censor::censor::censor: when it's time to groom him. It's a 2 person job and after he bit Brian while he was holding him I said no more. I took him to the groomer's to have him clipped down, worrying the whole time that he was shredding the girl to bits.
Once he was done and I arrived to pick him up I asked the girl how he was, sure that she was going to tell me never to bring him back. She told me how wonderful he was and that he purred the whole time. I was dumbfounded and the girl didn't believe me when I said what a menace he was to comb.
After he's been shaved I've found it easier to control the coat as it grows so he does not mind as much although on some tender spots like his armpits and his belly he does not like being combed at all. I have still not figured out an easy way to get to these areas.
The point to my rambling is that maybe Barney would do better if he was groomed by someone else. I'm not sure if you've tried but have you tried bringing him to a groomer that does not use a seditive to see how he reacts? I think sometimes they know they can get away with being fresh to us but around strangers they maybe a little nervous and unsure. Although this can always backfire.....
I'm certainly not an expert at grooming but as I've gone I've learned a little. Make sure you're using the proper tools for his coat. I think my biggest mistake with Sampson was that I had a comb that was too fine for his thick hair and it pulled too much. After reading a little bit I went out and bought the right combs and brushes for his coat which make things a little easier.
It helps too to have a helping hand if you have an extra set laying around.
I'm sure some other members would be able to help you out more.