gibby

Hi all. I have a 2010 Diesel Roomster with 110,000 on the clock. It's been good as gold for 10 years but has decided to fail today. It started fine this morning. I stopped somewhere to make a call and the lights all came on, everything working except it won't start. This has happened 3 times since and the garage can't find a fault and it started first time for them. The engine is not cranking and there is no ticking from the starter motor. The battery is just over 2 years old. The starter motor was replaced less than 6 months ago. The garage state its not the alternator and the battery is fine, although I have noticed for the last few weeks it sounds sluggish in the morning unless it has had a good run the day before. I can bump start it very easily. Has anyone any ideas on what this can be? Thanks, G