Need some advice.. l live in an upper cottage flat. my downstairs neighbour has pointed out that the overflow is gushing at times. she first mentioned it had happened whilst we were on holiday for two weeks and no one using water etc. apparently we came home and it stopped. she has now said it flows early in the morning and sometimes afternoon aswell. my partner had checked the tank in the loft area and all looks as it should. not sure what the problem is. any help woud be great... if l see my neighbour approaching me again before l'm even out of the car from work,think l might throttle her.