End of tennancy cleans are undertaken for letting agents, Managing agents often only deal with Estate management, 90% of our portfolio are for these such companies. (Management companies is if the residents them selves handle the estate budgets, service charges etc, however the free holder or management company normally instruct a managing agent.)
Getting in with one of these companies is hard but well worth the effort, as they then use you for all their sites, and rely on you more and more.