well firstly the location of Wai is way out on the map, it shows south end Patong and it is actually located at Loma Park north end of Patong, and Wai is the far north end corner of this buiding facing the beach
If you are walking it would be a long walk from where your hotel is but doable! I will take you from beach end of Bangla Road to make it easy for you
If you are standing at the exit of Bangla road facing the beach, turn right and walk along down this road, you will pass Thara Patong Resort entrance to the restaurant (dolphin water feature out front) on your right and just down from there Impiana Resort on your left and beach side, keep walking.... you will come to a road (Sawatdirak Road, it leads to Thara & Salathai resorts) cross here and keep walking.....nearly there couple mins, just over the road on the beach side (to your left) is a big whitish colour building, this is Loma Park, its like a big food hall type thing, there are many that will try get you in but don't give in Wai is right here,,,, it is located on the far north end corner of this building facing the beach in its own little corner and the food is great and cheap, we have been going there for 3 years now.
OR get a tuk tuk down and walk back, just ask for Loma Park north end of the building opposite to Finnigans Irish pub and you should find it easy enough
hope all that is clear as mud lol