Toyota Repair: 2008 sienna needs new ecu

Question
Hello,
My mini van started chugging and three lights came up on the dash. the dealer changed the transmission sensor $500. two days later same problem. They said that the ecu needs to be replaced $1300. they said that the trans sensor failed due to electrical problems with the ecu. I asked why they hadn't figured that out in the first place. They said that the code the first time didn's show ecu problems. But now they determined that it is the ecu. does this make sense to you? Thanks

Answer
No, doesn't make much sense, sounds like they are misdiagnosing the whole thing and not addressing the real problem, I'm not ruling out the ECM I'm just saying they are guessing is what it sounds like to me. I would offer you two choices, let them replace the ECM under the condition that it fixes the problem, if not they have to remove it and put the old one back and you pay nothing including the previous repair which did not fix the problem, if the ECM fixed it ask for a refund of the previous repair, again, it did not fix the problem.
The other way to go is to not deal with them at all and get another diagnosis and opinion from another dealer if possible, that's the best I can do without having some actual diagnostic code information and what exactly was replaced previously.