Two girls have been cleaning our house for a few months now, and i'm thinking of switching to my neighbour's cleaner ($10/hour cheaper). For what i pay, i'm not happy with how slow they work as it means that they don't clean everything. I had already extended their time by an hour, and all of a sudden they still can't get everything done. They take their sweet time.

They come every other week - am i obligated to give notice? Can i just tell them i no longer need their services because i am on mat leave?