As MC said "CHANGE the transmission fluid, don't flush it."
Let me add: Keep away from the quick change places. We hear far too many horror stories about them. Some may be fine, but many pay the help little, demand fast changes and that results in a high percentage of errors. Too many live by selling you something you don't need at inflated prices.
Find a good local mechanic and stick with them for your needs.
Don't go to the quick lube places, even for directions.