Great to hear that you have talked to May and can offer sound advice.
This is the first time I’ve heard of high oil consumption and explains an indistinct comment I partially heard on May’s video where the garage staff talk about I think oil and say something like “that’s guaranteed”. Even a local Norwegian living here couldn’t make out the conversation!
As Trikey mentioned earlier in the thread, if they managed to overfill the oil, maybe they “checked” the coolant as well.
Most garages and owners when they first see a KV6 manage to overfill the expansion tank, I did the first time. Next day according to May the engine overheated, airlock, nowhere for the expanded coolant to go, leading perhaps to over pressurisation of the cooling system and the leak into No.2 cylinder? There’s little doubt that the IMG has been compromised, a Swedish mechanic with 35 years experience said he was 100% sure.
So May, the customer, agreed that they should remove the cylinder head - poor dear she has absolutely no idea what a cylinder head is or does, she would say yes! Now even if the garage decide to reassemble everything it is doubtful if they have the specialist tools for the cambelts, not everyone is capable of making their own as you have done
I understand that May is a member of the Norwegian AA perhaps they can assist in any arbitration.
Good luck today May