I agree. When you do get things straightened out you need to service your transmission every 25-30k miles regardless of what your owners manual says. A proper service includes dropping the pan and changing the filter. $300 and $400 is way out of the ballpark for this. Do find an independent transmission shop to do the servicing. STAY AWAY from the large chain shops, you could run a brand new transmission in front of them and they would find a way to sell you a rebuild on it.
transman