Are you asking if you are entitled to cancel?
Ok. Are you asking if that is lawful?
Not on this basis I'm afraid.
This is a bespoke item so the usual CRA rules do not apply.
The right to reject is not automatic essentially because they cannot just sell a bespoke item to somebody else.
There is a duty upon them to provide you with goods of a satisfactory quality but they are offering to repair the fault which is perfectly adequate in law.
There is a capacity in law to refuse this company to allow repair on the basis that you have 'lost faith' but you are not describing grounds. You would have to have sound grounds to believe they are not capable of repair and you are not describing a reason here.
In any case, all that would mean is that they would be liable for the cost of getting another tradesman to do the repair rather than a full refund.
I'm very sorry but their offer to repair should be accepted.
Can I clarify anything for you?
Oh yes and they are liable but not for a full refund.
No. Nobody is liable for a full refund.
Unless, of course, the repair fails.
Or you can prove that it was done by the courier rather than despatched in that condition but I wouldn't go down that road.
It doesn't matter who caused it. They are responsible for the actions of their agent.
But then you return to your rights under contract and they are entitled to try to repair.