Chris Windermere

I have a mainstreet with the 3.6 engine and have transmission problem its downshift hard sometimes up too. I don't know what to do I only have left 1 month factory warranty. is it worth it to see a dealer? I found out the previous owner took it back many times whit different kind of problems however nothing was fixed just checked. I know dealers are very tricky they try to squeeze out all your money I just want to know if they will charge me for the diagnostic? Thank you!