My dad has a zetec mondy and I always do belts at 25,000 miles/3 years with new tensioner on mondy, cossie and other halfs astra, a belt kit is so much cheaper than a engine.
The last V6 omega I did broke all 24 valve guides, and bent all 24 valves, all in all around £1K to put right, vaux recommend 80,000 well they did they have halved it now, wonder why ?
Nearly all the ones i have seen have been due to tensioner failure, suggesting the tensioner cannot hold enough grease in the bearing to last the mileage.
The astra I just did had done 24,000 but the bearing was rough and noisy.
Anyway glad you got it fixed, could have done without a bill just before x mas though!!
tabetha