John Guest, a semi-retired IT consultant from Poole, booked his powerful sports car into Sandown Mercedes to fix a problem with the on-board computer but just hours after dropping it off, he received the fateful phone call.
The distraught owner said: "When I took the car in I told them there was also a problem with the traction control system but I was assured nothing was wrong.
"Later that day I got the phone call from the garage to say my car had been involved in a crash.
"My first concern was for the safety of the driver who thankfully wasn't hurt.
"The dealership tried to take it directly to a bodyshop but I demanded to see it.
"I thought the car might have been involved in a minor crash but I couldn't believe it when I saw it - it was totally written off and will have to be scrapped."
The dealership maintained that the car was being driven 'legally' and 'sensibly' at the time of the accident and that it had 'co-operated fully' with authorities on the matter.
The vehicle in question is one of the most potent in the Mercedes-Benz range, boasting a 630bhp V12 engine that is capable of catapulting the machine from 0-60mph in under four seconds and on to a limited top speed of 155mph.
"There was a tear in my eye because I have so many fond memories of the car. It was a car for life and it's irreplaceable," he said
"The thing that angers me most is the suggestion the car was being sensibly driven.
"Thousands of cars drove down that road that day, only three crashed and mine was the only one to be totally wrecked.
"It's negligence on the dealership's part.
"It is very galling given that I haven't done anything wrong. My only mistake was leaving my car with the dealership in the first place."
Mr Guest has since been given a Mercedes-Benz E350 as a courtesy car but is considering taking legal action against the dealership.
Gavin McAllister, managing director of the Sandown Group of Mercedes dealerships, said: "I was distressed to learn of the incident with Mr Guest's car, and I'm relieved that no one else was involved in this unfortunate accident.
"As soon as it happened, we co-operated fully with the authorities, and the police have confirmed that the car was being driven legally and sensibly in the road conditions.
"This is cold comfort for Mr Guest of course, who is a loyal and valued customer, and I along with everyone in my team at Sandown are committed to doing the right thing by him.
"We're working closely with the insurance team and are keeping Mr Guest fully informed throughout.
"Of course, we've provided a new courtesy car to keep him mobile in the meantime.
"Thankfully, incidents like this are very rare, and our technician is making a good recovery