Unfortunatley the guarantee does not cover for water damage.
The other route could be claiming thro your house insurance if your covered for mobile fones or bite the bullet and by an off line handset.
This kind of damage can occur while using the fone in wet conditions etc.
I have the Nokia 6111 also and the only issue I had was when the slide was extended sometimes the mic cut off ,which meant I could not hear the other person but they could hear me.
In connection to the other posts I can only repeat the advice given before. Take the fone to a nokia Repair centre for a firmware update to see if this cures the problems of freezing screens etc.
Nokia n8.
iphone 4 16gb - black
Be happy !!