Hi Retepg,
Last year(Late March) although pretty full, KN Guesthouse was taking walk -ins. Whilst I was staying there, a couple of German guys took the room reserved for a BM so he had to take one two floors higher than the poolside room.
Its a nice hotel, great pool and decent food. Located about 100metres on the left up Soi Jintana opposite Royal Paradise.
Rate is up from when I stayed, but still worth the money they are asking.
KN Guest House, perfect comfort and location, Phuket Island