Hello Zoe,
Although the compression test has revealed a significant ‘mechanical’ issue with the engine, at least it has eliminated the need to waste money on injectors etc. to no avail.
I notice the reference to a warranty, which was not known about before. Does that mean you have only recently purchased the car - or the warranty?
I think the all important progressive next move is to obtain copy of the compression test results, and to start a written exchange with the warranty company.
As always, we can only advise on an ‘if it were mine’ situation, and if it was, I would certainly discontinue any DIY mechanics on this car. It could leave you open to debate as to whether any faults have been aggravated by your ( partner’s) actions.
Perhaps you could keep us up to date Zoe, and if we can help, we will.
Good luck in getting it sorted.
Kind regards,
Gareth.