What do you mean stiching? Doesent it want to come out o top gear?

Try changing the transmision oil or check if you hany any play in the gear selector where cables meet the transmision

Is this a 5dp manual? And does it feel 'lost' as you try and take it out of gear? If so, this is a 'feature' of this box. No idea why, it's a development of a box that PSA have been using for nearly 40 years without much trouble, but around this time there is something about the arrangement that means that if you pull it out of 5th the 'wrong' way it can get lost, with the lever out of 5th position, but the box still in gear. It occurs if you let the lever drift over to the left as you take it out of gear - easily solved if it happens by shoving it back in; and easily avoided if you're careful how you take it out. If you experiment you should be able to determine the sort of move that gets it out of gear, and the sort of move that gets it lost, so you can avoid the latter! My 307 did this, but even though I was aware of it I sometimes got it wrong...