The transfer box on my 2013 Vauxhall Antara requires replaced as the bearing exploded and cracked open the casing. The garage have informed me that although all my tyres are well above the legal limit, and it had passed its MOT only 3 weeks ago, that one of the tyres has more wear on it and this can put pressure on the transfer box. I also have lifetime warranty or 100,000 miles but they are saying I cannot claim against this and have to pay £4100 for a new one. Is this all true?