clutch and collar change in Opel Vivaro

Hello!! Good to see if someone can guide me.

A month ago I found brake fluid under my Opel Vivaro 1.9 DTI of 2006, and the clutch pedal on the ground.

I take it to the workshop and change broken clutch necklace and put new clutch kit.

When taking her home without problems. Three weeks later when I drive again with her, I find that the first, second and third are very hard, 4,5 and 6 without problems.
With the car fully stopped, the marches enter well, but when the van has a bit of inertia, it is impossible to put the first, and the second scratch is underway and the third cost until it is taken out.

Today I have taken it to the same workshop, they have purged the brake system and they tell me that it is already normal to go so it is new and that it costs it. I tell him not to be able to put the first or that scratching the second is not normal. And he tells me that there is no solution. Well typical discussion.

I believe that the collar has mounted, or enough pressure does not reach it. I think the workshop does not want to return has to have a box and start investigating.

Someone could tell me that he can be failing with these symptoms that I have described.

Thank you so much and I feel the parraph.