Except as may be expressly authorized by these Rules or by statute, no other forms of prehearing discovery shall be authorized or permitted including, but not limited to, interrogatories and requests for production of documents and other materials
Ga. Comp. R. & Regs. R. 480-40-.05
O.C.G.A. §§ 26-4-27, 26-4-28, 50-13-13.