Failed @vauxhall Zafira Gearbox

[BankFodder]

Your post is a bit of a rant and doesn't tell us things such as how long you have had the vehicle, whether you bought it new or second-hand, how many miles you have done if you bought it second hand.
We don't know how much you paid or who you bought it from and whether it was bought on finance and whether that finance is simply a loan or a hire purchase agreement.

At least that.

In terms of they wear and tear exemption on a warranty, it is probably entirely reasonable because otherwise people could keep on claiming on a warranty long beyond the normal and reasonably expected life of the vehicle.
You don't tell us what is meant by a "lifetime" warranty. Do you mean your lifetime, the life of the car, the life of the guarantor, or the life of the world, the universe and everything else?

If you could let us have your story in a more structured and informative manner then we can probably give you some advice as to where you stand.

Certainly if there is a known design fault and you can show that the gearbox failure is as a result of that design fault then you should be in a very good position to recover the cost of repairs although it would probably have been helpful if you had informed the other side that you are about to do this before you went ahead. (Maybe you did)