I took my car to a main dealer garage for a diagnosis/repair. They changed a part, which I paid for, but hadn't fixed the fault. They had it back in and found another part that needed to be changed. As it was so expensive I declined and told them I'd take the car away, unfixed, with the intention of getting a local garage to do it. I was a bit annoyed about paying for the initial work so I spoke to the consumer helpline who advised I query it based on being misdiagnosed, not using appropriate care and attention and not fixing the problem. The garage agreed to investigate further and sort it. I went to pick the car up today, after being told yesterday that they couldn't fix it (this is 2 months after originally taking it in) and was surprised that they were intending to charge me for the new part I had initially declined, as well as some other parts which also haven't fixed the problem. I said I wasn't going to pay for these new and unnecessary parts so they are going to remove them, which is fair enough. My question is, how do I ensure they don't sit on this for the next few weeks/months. It's quite a complex job to remove the parts so there isn't much incentive for them to get it sorted...
You might want to include the manufacturer they represent in any and all communications once you inform them of your problem, making sure that notification goes to the top as well as the set letter crew.