Dear khun Nop,
Just hang up the phone with Go Thailand Tour (who provide ground transfers in Thailand and office space for Suntrips staff in Bangkok), they informed me that Suntrips also owned them money as well. They are contacting the lawyer and will process the legal action with Suntrips.
Go Thailand Tour suggests that the hotels in Phuket or in Thailand set up the group and proceed with legal action with Suntrips.