BMW 5 SERIES E39 323 1999 AUTO?

ABS /ASC lamp illuminated on dash ,no dials are working or fuel gauge, car goes into limp mode in 3rd gear only, transmission code PO700 transmission control system malfunction. have changed all 4 abs sensors , still no luck ,checked all fuses ,they ok. battery fine , transmission oil & filter changed, still nothing happening ,unable to figure out what next to change, has any-one had same problem. can anyone please help me. unable to drive car in 3rd gear only..the dash tends to shut down and warning lights pop up. cheers.