We had them at work...... yes! in the building lol, Imagine lay there during a hot stone massage thinking *oooo that gently tickly feeling is very relaxing* while im sat on the stool drinking a cuppa and letting ants run over your back hahahaha.... but back on track, The powder didnt work, the poison didnt work, and in the end we phoned the exterminator, Its a shame you dont live local, he only charged £35 for the whole building to be done.
When i moved into my house we had ants coming in from the front lawn, but the landlord had already called someone and i came home from work one day with a note pushed through the door saying "pest control been, All under control" it was very nice actually

lol