Inform your local authorities about this attack. Its falls under Cyber Terroism. Provide any logfiles you have (e.g. IP adresses of attacker, attack time) to the authorities. They will find and punish them. Its illegal in every country around the world. Its the same as someone breach into your house and vandalise them. More importent if you have a online shop and its hinder you to gain profit you could charge the attacker for the lost money. In which country do you life cath? I might can provide you help.