we have used this company for about 6 years. You have to pay a bit more but you do know that the cleaner is getting at least minimum pay rate and no less; that you are insured for any breakages or issues caused by them and that you have some recompense if you need to contact company to change the cleaner. We have had a number of cleaners over that time but all of them have been good.

http://www.selclene.co.uk/agencypages/docklands.htm