Flies everywhere in the store

I went to Nandos with my wife to get some lunch so we decided to eat in but immediately when we arrived every chair had on it a group of flies, and I remembered that in 2014 February my cousin also complained about the same thing we placed an order for food for eat in still and while were eating we constantly were disturbed by the flies and i then asked to speak to the manager Her name is kenty about the issue and Her response to the issue, was that there's nothing they can do about the matter because when they start in the morning they spray but further than that there's really nothing they can do about the situation.I then told her that my cousin had complained to me about the same issue at the same store and why haven't they fixed the issue though and she maintained that spraying in the morning when they start is the best they can do the flies are just uncontrollable.Which was a lie because other restaurants are not plagued by the same issue