general problems of the 2008 Mazda MAZDA6

Driving 2008 Mazda 6 when the at light came on and the automatic transmission slipped from gear reengaged very harshly into third gear. The 5 speed automatic transmission dropped 4th and 5th gear after re-engaging.

1. There was no warning to this failure, I was on a motorway (u. K) I check my oil levels every single week 2. I had an engine over-run and could only be stopped by switching the engine off, the rev counter hit maximum and a huge cloud of white smoke was left behind me. Consequences are now I am left without a car and I could have died because I was approaching a roundabout 700 yards away and swerved between 2 lanes of moving traffic to force a stop on a lay-by. 3. Nothing was done, Mazda are blaming me for the incident even after I had my oil checked and results shown a 62% diesel oil contamination, they blame the dpf (diesel particulate filter) for this over-run as I am not doing enough "long journey" miles. Which I was, no warning lights appeared before or after the incident and the oil levels are dramatically above the full mark. No fault codes are shown on Mazda computer. My car is sitting useless on my drive as we are all to scared to drive it.