Looking for taekwondo classes in nha trang for kids

Hi guys. New to nha trang and my boys love their taekwondo. Can anyone reccomend a good school? Boys are 10 and are 1st dan blackbelts, looking to keep up level and of course improve.
Thanks all...

Black belts. Congratulations !    They can try the Nha Thieu Nhi in the evenings on the west corner of the six way intersection below the Catholic cathedral.  There are outdoor evening martial arts classes there. If they are not taekwondo, the instructors should be able to direct your boys to another class.