So, to be thorough I'll start at the beginning.
Went 4x4-ing, diff lock took a while to engage so I went on without it (light still flickering, hoping it would engage). On the obstacle I got a bit stuck and to get out had someone pull while I try and get a bit of grip, but when my rear wheels started to lose grip I heard a clac clac clac as the lock was trying to engage and I immediately switched off the locker (and the clac clac stopped as I pressed the button). Got the diff lock engaged later the day before a different obstacle, so don't suspect damage there.
Only relevance here is that after that clac clac my ABS warning light remained on (I have it sorted now, was just a little nik on the sensor cable, so repaired the cable and no more light).
At the end of the day went to inflate tyres (at this point ABS warning light was still on, but no others). On the way to the fuel station, about 5KM, while accelerating, reaching about 100kph the vehicle was jerky, sort of losing and getting power. It stabilised when I slacked off a little. Pumped tyres, checked some fuses to see if something blew (trying to sort out the ABS warning light) and when I started the engine again my CEL came on. Drove home, no power (assume we went into limp mode - shifts gears at 2200revs and in 4th won't go above 2200 revs). Checked my oil (this was about 3 days after a major service done by Steve's in Milnerton) and found it was overfilled, both engine and gearbox, by nearly double the volume (I admit I didn't check the gearbox oil with the engine on, which I know I should've done):
Took vehicle to Steves Auto Clinic, sorted me out with a new Suction Control Valve and found the nik in the ABS cable. I'm now R8k down. Picked up the car from Steve's. They said oil was fine and they didn't touch it, but I checked the engine oil anbd it was filled to the top dot exactly (in the photo it's filled to the '8'). So they had to have taken out some oil

Quite concerned about this. Should I take vehicle in to Mitsu or back to Steve's or has anyone had this or similar? Any suggestions would be welcome.