Need Camery advice

Okay i know its not a Tacoma but your the only help i can find who might be able to answer competent questions to and get some advice, I have a 2012 Camery with the little 4 bang engine that runs great along with the 6 speed auto. trans with 185,000 on the ticker, the tranny has been acting a little sluggish lately and since bought new has never had a service done to it and after calling the local Toyota garage, they said they do not change filter just suck out oil and replace for $350.00, im not a dummy and didnt want to argue but does this sound correct? i know there is a procedure to this but surely the filter has to have residue inside as it was intended or is this normal? ive looked everywhere for answers but it seems the smart people hang out here so can any of you advise? Thank You for your time in advance!