Sorry I've not posted back about this.

Update: It's SOLVED!

I took the car back to the mechanic after driving around with the flashing lights for a long time. He's fixed the problem with the glow plugs (some kind of wiring problem). As for the V157, he raised this issue and said it need's to be replaced, and until then the light will come on and go off intermittently, which it does.

It seems that the replacement of the oil pump has fixed the issue of the oil and fuel mixing and then becoming a runaway.

Thank you all for your help