hatch door of 2008 vw golf

I am having trouble with my rear door of my golf. I open the hatch and won't stay open. The manual doesn't say anything about the rear door besides how to close it and how the lock works.

I have had the car for only 7 months and I don't know weather to go to the dealer or a vw certified mechanic. I'm not sure what the price difference will be if any. I read somewhere about the hatch shocks might need to be replaced but I don't know if my warranty covers that. I probably answered my question even though It will probably cost me a couple of hundred dollars to fix.