Hi, I have a matrix 1.5turbo. A month ago, a half full tank of diesel was topped up with nearly half a tank of unleaded. This wasnt noticed and had an mot and full service 5 days after the occurrence but started to lose power and project black smoke 2 days after this. We took it to a local garage who had it for few days before diagnosing the smell of petrol in tank. The tank was drained and we were advised to keep tank full of diesel and would eventually right itself. After 10 days of this there was small improvement but it still had no power going uphill, still churning out black smoke and not starting up well. Took to another local garage who drained the tank again and told us if problems persisted to take to main dealer. after 10 days it has improved a bit but don't know how long to leave it. Some friends and neighbours have told us anecdotes that maybe will be few months but...mmm...help?