oil preser light on again

Hey Guys, Hoping someone can help, I've just got my car back from the garage who replaced the broken turbo. (£1232 later) When I got the car back, he stated he has fitted the new turbo and everything is fine except this one light on the dash. So a Red 'Oil pressure: Engine Off!' light comes...

My Car has now done 130,000 miles. At around 120,000 miles, the oil pressure light came on. It went into the garage and they cleaned the oil pickup filter in the pickup pipe. This worked for around 5,000 miles and the light came back on. I added engine flush and drove it home from the garage. (2...