Woodpecker attacking house

A woodpecker has decided to dig holes into the wall of our flats. How can we stop it without causing it any harm?

The bird, a great spotted I think,  has pecked three holes through the external cladding of our block of flats. Once through the holes he or she is digging out the the insulation creating a cavities approximately 30cm square. It's not nesting season so I can only assume it thinks the insulation granules are insect eggs. It can't be good for the bird and its definitely not good for the flats - the residents are complaining about the noise and there is a risk of wider damage if the weather gets in. 

We have had the holes filled in three weeks ago but almost immediately the woodpecker came back and re-opened one.  What can we do?