I once bought a ticket for a service from the ticket office, only to be told it's a rail replacement bus after purchasing! The irony is, I could have travelled on a bus to my destination free of charge with my English National Concessionary Travel Scheme travelcard. I paid because I wanted the convenience of a train that has a toilet should I need it and to avoid the nauseating feeling of travelling by road on winding roads and also to enjoy some beers. People will quote me saying that the ticket is a contract to take me to a destination and as long as the operator fulfils that then they have done no wrong, but I felt short-changed going to a railway ticket office and purchasing a railway ticket only to be told my transport will be a bus! I'm not going off topic here, it's a valid comparison but it's similar to paying to stay in a Hilton Hotel only to be told after booking that you will be staying in a Travelodge! There was no signage at the ticket office or the approach to it advising that it would be a bus service. To answer the OP's question, fares are calculated in advance and it would not be possible to alter the ticketing system every time a replacement bus service is used. They could possibly adjust Advance TOC specific tickets if they are aware of the disruption ahead of time but I don't believe they have the technology to fluctuate the fares based on disruption. Station facilities also must be paid for, such as toilets, customer service staff and of course ticket office staff.