Can I please get a price range for transmission work on my 2005 Touareg?

What is your question?

About a week ago I noticed that a brownish looking liquid under my Touareg. I took it in for my mechanic to look over and paid $160 for sealant for hoses. I also needed 4 tires and my total bill was $990! Drove my Touareg over the next few days and noticed it was still leaking -- called my mechanic to inform and was told I should "bring it back" that Saturday. While driving to the shop I noticed a "thump" when I pressed down on the gas. My mechanic then stated that although the sealant for the two hoses were no longer leaking, but supposedly the hoses that ran below and behind the transmission were leaking (?). (So, why wasn't this noticed before the charge of $990!) Regardless, now my mechanic is stating that the parts and labor to do this work to stop the leaking will be an additional $1000 -- can someone explain why?! Should I go to a transmission specialist or maybe go back to the Volkswagen dealer -- the dealer may be a little expensive but I never had to go back a second time? My mechanic stated that the $1000 is a discount -- is it really?