Baits can work, but only as large quantities over long periods of time. What's worse, as the colony is stressed, ant-feeding behavior may change, and baits become ineffective. Because the supercolonies contain tremendous numbers of ant workers, brood and queens, even if you kill large numbers of ants, replacements soon move in from unaffected areas. Pharaoh ant supercolonies in and around a building require that you bait, evaluate and rebait each infested site for six months to a year. You may also need to bait outside or apply a perimeter treatment.
Permanent solutions are difficult, but possible.
For other ant supercolonies, permanent solutions are rare. Service is never easy. When something isn't working, then you try something new. Perhaps you try to track down and treat individual colonies, change baits once again, apply perimeter treatment, etc. Just as important, the customer must be aware, up front, that control of these kinds of ants is a process that must be continuous.