If the DWP thinks that a rent payment or service charge is excessive, they can ask a rent officer to look into it. Where the rent officer considers that the rent or service charge should be a lower amount, that amount will be used in your housing costs amount calculation, unless the DWP believes that it would be inappropriate to do so.
UC Regs, Sch 4 , para 32

Factors that should be taken into account include whether the rent or service charge is unreasonably high compared to the area you live in and what would be paid in the private sector. However, other circumstances that apply only to you should be taken into account, such as whether or not your property includes adaptations to enable you to live there.
Advice for Decision Making, Chapter F3 , para F3254