Yes you can apply. Call the number
https://www.gov.uk/contact-ukvi-inside- ... thing-else
and provide initial IHS numbers and applicant details etc.
I have applied couple of months back and escalated in couple of weeks.
They were honest in saying these refunds take lot of time and no one can say when it will be settled as they have to do quite a few checks. The request can be escalated only once after that it is just waiting game.
I know this is not going to be easy, but yes you can apply rather than not applying.
we were just about to finish 3 years in old tier 2 visa when we came to know about this and we applied immediately. So we are expecting atleast 2.5 years (refunds are processed for every 6 months of eligible period from March 2020) of IHS for 4 members (its a huge money)