2000 Renault Scenic diagnostic code

Transmission problem
2000 Renault Scenic Front Wheel Drive Automatic 82000 miles

hi I ve got a renault scenic with no forward gears but I have reverse have had a diagnostic test and have been given the code po 08706 it has cost me 70 pounds and he came bk to me saying it was the barrel in the gearbox had smashed up not sure if he was all that compitent and cant keep paying money out have not got it would really appreciate nay advice pls the scenic is a 1.6 16v