Citroen C4 no drive (automatic)

Sometimes it works when it’s hot until it changes gear into second then it’s back to no gears and warning sign saying “ gearbox fault
Leave with ignition off for a minute and sometimes it works but then stops again and the same warning signs come back and nothing. A small of very hot oil comes as the engine gets hot . I am just about to dump ot on the nearest scrap yard. It only done.27500 miles and it drives wonderfully before this problem started. All the simple things have been checked fuses contacts oil level no fault codes when checked , when it stops working all things like reversing lights parking sensors, mirrors lowering rear wiper , all electrical things supposed to happen when gears selected stop working .Anyone any ideas on what’s wrong please let me know