Infestation problem..

Tax Planning and Financial

Hi there,
We have just experienced a problem in one of our houses where a tenant seems to have brought in bed bugs and not noticed it until it is now a major infestation.
We have Environmental Health coming in to treat the infestation. It has created a number of other issues in terms of accountability ie: who is responsible for various costs to put everything right.

I would like to ask you for some advice please; as although we always strive to be fair and reasonable this problem has high-lighted in our opinion some gray areas:

A tenant has allowed bed bugs to multiple in his room for 2-3 months, according to the vermin inspector, such that the entire house is now totally infested and the cost to rectify is potentially going to be over £1000. Is it reasonable to keep the tenants deposit under such circumstances?

and if another tenant is unable to live at the property for a week due to the infestation which she is allergic to, does she have any grounds to claim a refund of rent for that week?

I would really appreciate as quick a response as possible please as this needs urgent attention.
Many thanks for your help.
Regards,
Jules Palmer