Timbo Slice

Howdy,

1st time posting so be gentle. I need help!!!
I have been having some issues with my 5 speed auto transmission for over a year now.The car has done 138,000 kms.
The story goes as follows:

* AT Temp Oil light starts to flash every now and then.
* Had my regular mechanic hook it up to his computer but no hard fault recorded. Mechanic resets the error... 
* Car starts slipping gears under light load at low speed. Up a hill for example
* Got fluid flushed by Subaru. Same issue occurs.
* Subaru finds out the the transmission computer has been wiped (I assume by my local mechanic) and needs to be re-learned. Which they do.
* Car would still slip gears usually between 1st and 2nd or 2nd and 3rd. Often after the car had been driven for a short period of time and stopped for a short period of time.
* I still get the At Oil temp light showing up every now and then which I could get rid of by turning off the car and re starting again.
* This happened all through winter and about a month ago I started having more serious issues...
* My car would not start. I have full electrics and Accessories but no starting what so ever. To me it seemed like the car was in DRIVE which it clearly wasn't. 
* I noticed that if I get the AT Temp Oil light flashing then after I turned off the car and attempt to restart, then it would do this. The only way I could resolve this was disconnect the battery and then reconnect after a few minutes.
* This got so bad and I noticed other weird things like the drive "D" disappearing from my dash occasionally or the transmission would get stuck in 4th for a few minutes.

* I finally got the car to Subaru while the AT Temp Oil light was flashing and it determined it was my AT Range Switch Circuit Malfunction - code: P0705.
* Because it is an internal switch within the valve body the recommendation was to have the transmission replaced.
* The problem being it has been impossible to find a 2nd hand transmission thus far. Model: TG5D8CLAAA

* The strange thing is that I left my car alone for about a week while I borrowed a friends car and now my Liberty seems to be acting different again. 
* Over the last 2 weeks I haven't had the lights once nor have I had an issue starting the car. Only 1 instance where it slipped gears again.
* The only logic I have that here in Brisbane it has warmed up already. I'm so confused.

My question is:

Is it definitely the transmission that needs replacing or could it possibly be one of the ECU's? I would be super pissed if I spent thousands on replacing a transmission that didn't fix the issue.

Is there somewhere in the Brisbane area who could diagnose it any further?

Does anyone know where I might find a 2nd hand transmission. I've sent out a dozen inquiries and have Subaru looking into it.


Thank you in advance for taking the time to read this.