Toyota Repair: 2005 Camry SE V6, transmission failure, transmission flush

Question
Hi there, I was wondering if my car has a timing chain or a timing belt?
Also i took my car in for a transmission flush that was overdue, I am pretty
sure it has never been done before and my car has 160000 Khm. I seen the
fluid was dark and it needed to be done. soon after i got the transmission
flush i started to notice the gears shifting hard and seemed to be getting
worse. I looked at my receipt and it says they added dextron fluid with some
sort of blend to make it work with my transmission. i took it back today its
been about 2 weeks and 2000 khms later. They added the blend fluid again
and said to check back in a couple days my question is could this have
caused serious damage to the transmission if they forgot to add the blend
the first time? and is there any other possibility for the transmission to be
shifting hard at this time?

Answer
This engine uses a timing belt which should be replaced every 90,000 miles. The transmission requires WS ("world standard") fluid, this is what toyota requires. I have no idea what blend they used but it must be compatible to the WS fluid or transmission failure can occur.