Waterloo Honda

We had a problem with a transmission fix at Waterloo Honda. We paid for a diagnostic, but they made a mistake with the diagnosis. Instead of just replacing the shifter cables for $445, they ended up replacing the whole transmission for $2300. It turned out that the shifter cables needed to be replaced after the transmission was already changed, and that finally solved the issue. My father-in-law, who used to be a mechanic for 50 years, even suggested they check the shifter cables first, but they said they were fine when they weren't. We've been trying to sort this out with the service department, but the service manager left and the dealer manager won't call us back.