Here are some telephones of useful services in Santorini island that will certainly help you in case of emergency.
General Hospital : +30 22860-23123, 23124, 23125
Airport : +30 22860-31525
Port : +30 22860-22239
Police Station : +30 22860-22649
Post Office : +30 22860-22238
Bus Station : +30 22860-23812