These stories are very common, unfortunately for any tuning company or individual 'you are only as good as your last mistake'. The real test is how these companies/individuals put things right when it does go wrong however costly. Does Mr Bowkett give a lifetime guarantee on his work ? I would think that difficult for anyone, especially with PCP's given that 'O' rings might be considered a servicable item prone to wear & failure over time. I hope it gets resolved to everyone's satisfaction.
John
Law of any kind only affects those willing to abide by it.