Oh how i sympathise with you - they rampaged round my garden, too...digging up the lawns and eating bulbs.

In the end, we've erected an electric fence, which does work.

As far as repairing damage goes, I used to go round and scoop the soil back into the holes, and carefully replace the grass 'divots', stamping them down and watering them. It was a daily task, though, so try to find out where they're coming in, and I do recommend an electric fence. It's on a battery, so mains power is not required.