Transmission HELP!

[Lil_BeamerBoy]

I have a 91 525i with AT, no dipstick, filler plug on the side, with sports drive. I've been getting the TRANS PROG for a couple of weeks, so finally got down to working on my car. I was low on fluid and I had an almost full bottle of Dextron3/Mercon I poored it all in so that I can go get a transmission flush, it wasn't full yet. Then after my brother took it to where he works and I did a transmission flush, TRANS PROGRAM was gone but when he got home my car smelled really bad, like rotten eggs and while driving to a friends house later on that day, my AT started slipping when it changes into 2nd, 3rd or 4th gear, the next day got so bad, 2nd gear doesn't engage at all. Then I found out he wasn't aware of the procedure for a BMW transmission fluid top off, the tranny didn't warmed up the car so I was running on low fluid.

I'm open to any suggestion and thanks for any help given.

[Karl]

Drain the present fluid, fill the right way, and maybe you got lucky and avoided permanent damage.