I seriously doubt that any refunds will be given and also doubt whether they are warranted. You attend university for an education and learning isn't measured in "seat time".
It would be proper for the instructors to compensate somehow so that learning isn't impaired, but that doesn't necessarily mean holding lecture/tutorial sessions. There are a lot of ways to assure that students learn when there is some disruption. I suspect that the overall effect or intent isn't to just chop off the learning after a certain point.
It would be too easy to argue the above in any legal proceeding and, I think most people could be convinced, even if they haven't thought of it before.
And three days is a very short period of time in any case. I suspect that the three missed tutorials weren't all in the same class/subject.
It also seems to be the case that some of the things that the strike was seeking would actually benefit students; workload, for example.
Note also that higher education is heavily subsidized by government (tax funds) in most places, so what you might be "due" in any case is likely a lot less than you'd think. It isn't like buying Cadbury Chocolate.