Disappointed but kudos to Promise!

As a customer, I am disappointed and feel unfairly pressured. As I was preparing to sell my car, it began jumping out of second gear, so I requested a diagnosis from Michanic. The inspection report advised replacing the brake and clutch fluid, gear oil, and clutch kit, with gearbox repair only if the problem persisted. I proceeded with the clutch kit replacement (10K upfront). A second mechanic (Promise) later advised that the gearbox, not the clutch, was the underlying issue. I confirmed this on ChatGPT: the issue is specifically related to second-gear synchronisation and gear wear. I raised this with the office and was told that Promise first needed to “verify” the initial diagnosis???? The work was then changed to a gearbox repair, and the gearbox was stripped 3.6 hours later (3.6K). While the clutch disc showed some wear, it was clear that the gearbox required immediate attention. I am now awaiting Michanic’s handling of the next steps