Firstly i'd have a damn good sniff of whats in the tank, even a gallon of petrol if rthere should be obvious if you have a fairly keen nose.

Other obvious things to do are to check all levels, and actually look at the oil and water for contamination of either.

Is it still coming up with the warnings now if you restart and does it sound completely normal?

I would first suspect a connector to a sensor has come adrift or similar, as a result of the under-bonnet disturbance from the earlier repair work.

If your receipt says you put the right fuel in your tank, the chance of the forecourt pump dispensing the wrong fuel, or contaminated fuel, is very small. Not impossible, but very small.

Have a look under the bonnet in the morning, and check by hand every wiring connector plug you can see, just to see if one is loose / not been pushed home properly. If that doesn't reveal anything, take it to the dealer.

Thanks for your responses so far

I doubted it was contaminated fuel but thought if check out the likelihood of it happening; seems unlikely so that's ruled out!

I've left it overnight so will check it soon once TheBoy is feed and watered and then head off down the road. The manual suggests is nothing more than a service due just seems a particularly scary way to get the message across.

I'll post back my findings.........