looks like the 90 days has gone since the start of the 18 month contract,
That's the point.
It isn't available for joiners, but it still applies to people who joined while it was available, on the old packages. (Though it seems you had to opt in, which seems wierd for a guarantee! But that's history - except there seem to be cases of customers being told they didn't opt in whne they know they did. That's a different story).