After complaining to the dealer in a letter and receiving a phone call back with them not accepting responsibility I contact the Motor Ombudsman for them to decide. I'm happy to confirm the ombudsman agreed with me that it was unlikely the thread would be worn on a vehicle with low mileage and being removed only 13 times, that the likely course would be from being crossed threaded or over torqued. I have received a full refund from the dealer.
