I have exactly the same problem with the Wing fans. Out of 8 units, 7 had the problem with the speed control (no LOW or MEDIUM control, only HIGH). I called up Wing and they sent a technician. He said that he needed to replace the electronic portion of all the fans (before he even check or take a look at a single fan).

And I need to pay RM60 for each electronic replacement, and I need to give them back the old electronic part. I asked him why need to give back the old part, he says it is their company policy. WTF!!!

In the end, I only replaced 1 fan and decided not to replace the rest. Lets just say, I will NEVER ever buy a Wing fan again.