I played there in 2003 I think... polo was average but a couple useful athletes. I was there as a guest of FeelFree Kayaks. Try contacting them on:
Joy Sports company
9/11 Ratchadapisek 18 Rd., Huai Kwang Sub District,
Huai Kwang District, Bangkok 10310. Thailand
Phone : +66 (0) 2692-6868, +66 (0) 2692-8882
Fax : +66 (0) 2692-6611
Email : for foreign distributor please contact
info@feelfreekayak.com
for domestic distributor please contact
marketingthai@feelfreekayak.com
Hopefully that will help you