autobox problems

hello again had another problem occur with my c 200 sport ..driving up the highway around 70mph all fine. i came to an island a and stopped for traffic and as i pulled off it was like it pulled away i 2nd ,further up the road i noticed that it wouldnt change gear so stopped on the side of the road engaged park then back to drive.no drive,so i turned the engine off and then back on,engaged drive still stuck in 2nd.i had to travel 30miles whilst stuck in second(not nice).has any1 had this issue,is my autobox dead,or does the oil need to be changed.the gearbox code is 722,422,any ideas please as im not willing to replace the autobox due to the expense of it...lee:crybaby2: