Agree with the name and shaming of the company who sold a defective flywheel and take 5 months to organise a returns procedure, however I don't agree with the naming and shaming of Envy.
How many garages do you know would offer a discount because they have never fitted a part before? I don't know many to be honest, none near me would, they would quite happily attempt it, claiming to know everything there is about your car and spout rubbish to you in the hope to fob you off and then charge you full price claiming to have done a job they knew full well how to do all along. I think the discount price offered was honest and respectable.
As for the delay of getting the car done/checked, and the missing of phone calls and courier services, I think these are the expected rigmarole with car repairs these days and i think of all the 20 times I've had my car into a tuner to be upgraded/fixed there has always been mishaps and delays. The worst ones actually tended to be at Audi and BMW dealerships were I was paying a premium for their service.
I've had much worse time in the past with a tuner for the same type of problem that seen my car off road for a year, but ultimately it was the part manufacturers fault and I accepted that although the correspondences from the tuner could have been better, ultimately I was not the only car in that garage and these type of mishaps are to be expected.
Just my two pence!