4th Gear Problems

Hi all,

I seem to have the dreaded 4th gear problem on a 2019 RS.
Low rev heavy acceleration causes a jerky slip (?) type of thing but only in 4th gear. Yep I do have a quick shifter but haven't had any false neutrals for quite a while and tend to just manual shift.

My question is does anyone know of a good independent near or in Kent that could fix this?
I've found Tri-moto so will give then a call but no idea of any others.

Any help much appreciated.