For extending stay and visiting restricted places like Haa valley, Punakha, Phobjikha etc you need to go to Thimpu Immigration office....
About Wangdue Prodrang
The district of Wangdue Phodrang is in a pretty hot and dry valley. The temperatures were soaring in the vicinity of 35 degrees but nights were cool. I stayed at the Punatsangchhu Cottages, a really wonderful inn on the outskirts of Wandue, on the river side. The rooms are big and airy, with balconies overlooking the river, there are lovely jacaranda bushes growing all over with wonderful lavender coloured flowers.