Gear change issue C4 spacetourer

[mersey_mike]

I have a 2018 spacetourer 1.2 with a manual gearbox and 5th and 6th gears have stopped working.
No issues with gearstick, stick moves through gears as normal, but letting clutch out in 5th and 6th, nothing.
VERY notchy to get into reverse. Rest of gears work fine, no funny noises or issues.
Hoping this may be a gear selector/cable issue, but not sure how to get access to look into. Any help much appreciated

[Huskyxantia]

If them two gears are not selecting then the cables have gone. Web search produced this not sure if it will help? remember there's a lot of cross platform running gear between various models but all should seem to be repaired the same way