Actually they can because their is a lack of substantial evidence. Best case scenario, OP gets his case thrown out for naming and shaming. Worst case, they come after him for public defamation and loss of earnings.
What the OP needs to do is create substantial evidence as to how the work conducted by the workshop has destroyed the vehicle. When you factor in that it's a 10+ year old car, driven by someone who would be stereotyped as a 'hoon,' it makes the case a little harder. The onus will be on the OP to provide the required evidence which means talking to a proper mechanic and getting them to write up an expert witness testimonial which will explain in laymans terms why this shouldn't be happening.