The tenants will however enjoy the common property improvements with no change to rent, at least until the next review
Well, there has been a change of the conditions of their rental, hasn’t there? They have been paying for a facility that they haven’t been able to enjoy, plus the additional hassle of having to deal with its unavailability, so they aren’t really paying the same.
I’ll bet a week’s car space rental that if the OP took this to Fair Trading, she’d get a rent reduction.
Tenants don’t have any meaningful say in the running of their blocks. That’s one reason why landlords have to stick by the conditions of their lease, or compensate the renters when facilities are removed.