There is a suggestion that ID have no liability for the downtime since their contract in someway provides exemption for themselves, however under UK law there are several key pieces of legislation that prevent this, primarily the Consumer Rights Act 2015 (CRA) for consumer contracts and the Unfair Contract Terms Act 1977 (UCTA).
If enough people coordinate to take action then good outcomes can be realised for customers.
If you are in favour of being involved in action against ID for compensation during this outage, then I suggest you leave a comment below.