Hi All. The other day my wife's car suddenly refused to shift out of 2nd or 3rd gear, not sure which. It also felt underpowered, although this could be due to the gear it was in. On the dash the gear was in 'D' and I could not manually down/up shift using the Manual mode, and neither could I put it into 'C' mode, it was stuck in 'S' mode. I parked the car up and put it into Neutral then back into Drive and felt what I can describe a loud Thud in the back. This was repeatable when tried again. It was only when I switched the engine off and back on that the issue disappeared and all the issues I have described above where rectified. My wife has mentioned that this has happened before. Could someone please shed some light on this? Car in question is a 2005 C180k Sports Coupe. Full service history however I think its been a while since the auto box oil was last changed, could this be the problem? Thanks.