The Oyo State Signage and Advertisement Agency (OYSAA) has clamped down on third-party agents and other advertising practitioners for their refusal to pay advert bills to the state government coffers. The Director-General of OYSAA, Mr. Oludolapo Eso-Ajanaku said this on Wednesday, after leading an enforcement exercise within the Ibadan metropolis, according to a statement signed by Prince Dotun Oyelade, Commissioner for Information, on Wednesday.