Any company claiming to manage your property for 10% is not being honest about their business model. They recoup the costs by charging the guests cleaning fee's. This will directly impact your occupancy rate and you will make less money than if you did it alone. This is happening in London and most of these managed units have pitiful occupancy rates.
You want to be using a management company that has the technology to gaurantee you an occupancy rate of over 80%, for that privilege expect to pay between 25% - 35%. Your property manager should be commnunicating with you regularly to discuss strategies to improve revenue. On top of this they should have experience with and deploy proprietry machine learning based price optimisation that's trained for your area and local economy.
Anything less than this level of service in todays market is not going to cut it, part of a property managers role is to increase your revenue, if they can't do that you are better off employing a local cleaner and paying someone to look after your guest communication.