TXGuy

I can confirm there are none currently. They all have fair usage policies.

5M baht for 80 sq m. We're talking 60K baht/sq m. Would be tough these days to get one along the BTS lines within 10 stations proximity to Siam Square, even for an old building. I would try to look in Bangna area if you set a hard limit there.

Just wanted to mention another option for someone looking for True Data SIMs. I just bought mine from http://www.thaismileconnect.com. They sell True Move H SIMs with same selectable data plans and price steps as True. paid a little bit more on the SIM base price, but saved me a trip to MBK and a couple of hours of my time.