The dealer said that you needed something badly? really, do tell.
and let me guess, it was not gonna be free, either.
If the coolant is that bad, there is a pet-c ock (website won't let you type **** :P ) on the bottom of the radiator. open it out and drain the fluid. next, pull the lower radiator hose off. drain remains. next, re-fill coolant.
Start engine, let it idle for 15~20 minutes to "burp" the system. check coolant level often.
make sure the over-flow is full.
then go for a short ride. watch your engine temp. also re-check coolant level after your short ride.
Is your engine running hot? Can you see the coolant is dirty? Do you need to simply add a bit of anti-freeze to get it back in spec? (add at proper mixture ratio, verify with tester, simple tool with a few balls that float or sink) If your coolant is fine, I'd tell the dealer to pound sand. but that's just me.
Also, you need to fill the coolant in two locations. one is on the passenger side of the engine, right between the cylinder V's by where the plenum heads into the heads.
The other is the overflow container. you should have some in there incase it wants to suck some extra in while the motor is "burping" itself.