My reading of that would be a football season ticket holder would get say 25 games over the year for £1000, or £40 a game. If the holder had the opportunity to see 15 of the games, but the club haven't provided the ability for the holder to see the remaining 10, it would be fair to get a £400 refund.
However in the case of the railway, most services are still running. There may be issues with the new timetable (say there's normally a 7am train that you catch, but now the first train is at 10am) which could be considered on a case by case basis, but for most lines I believe the trains are still running. I wouldn't think minor changes to timetables and frequencies (say dropping to 2tph from 4tph) would be enough to void the contract.
The government hasn't prevented the railway from providing the service, nor has the railway (on the whole) stopped providing the service.
In some cases the government has stopped you from using the service, but then you wouldn't get better-than-normal conditions from the railway if you were laid off from work, or if you were called for jury service, or you were sent to prison.