Guarantor run away

Tenancy Types and Management

my tenant has broken yet another window. I dispare. I have replaced 3 keys in as many months, unblocked 3 loo's and a sink. Mum and sister are in prison. Her Grandfather is the guarantor and has run off with another woman. I have written to him at his last known address but the letter was intercepted by my tenant and the Grandmother. So he knows nothing about the 10 months of vandalisium and antisocial behaviour going on.
How do I trace him, is there a firm of people finders out there that could help.
I believe I am tameing my tenant some what and we are comumicating and fixing things, like cupboard doors and baby gates now, and putting out the rubbish, but I should not have to be her gardian, social worker, child trainer, mother and policeman.
Where is this guarantor, help please.