Keep calm and carry on?

Hello, I have a 2 year old sheltie who has a very thick coat, especially around his skirt and tail. When he was younger we did 'everything right' to get him used to being happy being groomed, making it a rewarding, relaxing experience and he was find until he hit adolescence. He is two now and I have tried going back to basics, pretending he'd never been groomed before. He pretends he loves being groomed, wants to get up on the table, but after a couple of minutes he gets bored, wants to bite the brush (I am having to leash him as they do in parlours, which I think is a bit stressy for him) and he really hates having his back end done. He is moulting loads at the moment and I hate struggling with him.

I took him to a local grooming place about a month ago because I was fed up and he came back and his skirt had not been touched. They are the only place near me I know of so I'm at a bit of a loss. He has been to a P@H parlour when we were on holiday and they did a fantastic job, but there are none near me. It needs done so he doesn't get matted, but what can I do to help him settle?

Sorry for the essay!!

Have you tried brushing him in the bath? Cheeko isn't very keen on the bath so I put him in there with no water ofcourse and brush him because I'm not very keen on losing my fingers

How often do you try his skirt? With mine if they don't like something then I'm afraid they are going to get it done 2-3 times a day until they are used to it!