Holy shit Roy, that's bad - you have my sympathies.
In case it's of any interest, although I guess it's of very little use, the owner of that animal has commited a criminal offence if the animal is out of "control and there is a fear that injury might occur". I'd suggest that the dog got to your kite, making it out of control, and that it tore it to shreds giving you real grounds to have fear that injury might occur (note - injury doesn't actually have to occur, you only need to be worried that it might for a criminal offence to have been committed).
Maybe the local rag would be interested in a "killer dog on the loose" type story? "Keep our parks safe campaign" etc...
BTW, if you buy grazing rights, a sheep and a rifle (and a license) you can shoot a dog that worries your sheep without warning - best to find a really nervous sheep for this.