Join Date: May 2017
Location: Maple Grove, MN
It's rare when a warranty - original or extended - mandates where the car can be serviced. It's probably best that you consult the terms of the warranty, but for the most part you should be able to have the service performed at the facility of your choice. However, since you may have future concerns about warranty and whether the recommended services are performed, I recommend that you get the best possible documentation of the event that you can.
And, for what it's worth, the service is quite easy to perform yourself, providing that you have adequate facilities, tools, and knowledge. An evacuator can be had from a variety of sellers (including Amazon) for well under $50, the brake fluid costs $15 (I use synthetic DOT4 and I buy a quart bottle and a pint bottle), and it can be done in under an hour.
Finally, in case there was concern that this is a "scam" or a B.S. unnecessary service: I flush mine in both of my cars every two years, regardless of mileage. It is one of the most often overlooked maintenance services and I recommend that everyone has it done at a regular interval.
Just because you can does not mean that you should.