Rent Rebate for lack of hot water

Maintenance

Hi there, can somebody please assist with my query?

Recently I've had to have a new boiler fitted in the house I rent out and my tenant was without hot water for 6 days, is there an appropriate percentage of rebate I need to make to compensate my tenant for not having this facility?

To give some context, she has a 6 yr old son and was able to access washing facilities elsewhere, however, I just wondered if it was appropriate to award a rebate due to the inconvenience?

Has anybody experienced anything similar? The rent is due this week so I want to make an offer (or not) as soon as possible and wondered if there was a ruling or general consensus about such things.

Cheers

Sharon