Mitsubishi Repair: Mitsubishi Galant viento 95 A-Trsnmission, mitsubishi galant, high gears

Question
hello linda,
i bought a Mitsubishi Galant viento gallant 95 that had 97000km on it 6 months ago on line from japan.2 months on and the auto transmission failed while i was on the road. shifted it to the high gears, it bucked and something in the gear box clanged.eventually i had to park it and had repairs done which involved changing all the gears which were totaled.for the next 2 months it ran with delay issues when starting from a stand still till eventually the gears got stuck on the 1st gear. another mechanic ran a check and discovered the hydraulic pump was totaled.problem is am confused whether i should just change the hydraulic pump or the whole gear box, and if am to change the gear box, will there be compatibility issues?.biggest issue is am in Uganda where expertise on automatic vehicles is very minimal.the car engine, fuel consumption etc are perfect.

Answer
Dunckhan: To me it sounds like a computer problem, as the computer has locked the transmission into a gear to keep it safe. But how you are going to code the computer where you are at, I am not sure. The clutch is run with hydraulic pump but the auto transmission has a fluid in it, also a filter. It would be a good idea to change the fluid and filter to see if that might help your problem. The fluid which is pink in color, if it is pink and brown it needs changing or all brown then it should be changed. I would take the car back to where they fixed the transmission in the first place and have them check their work. They might have not got something tighten down and something has let go. Why not get that fluid and filter changed to see if that helps your problem. Hope this helps and God bless: Linda