FGW continue to advertise this generous offer heavily. Stations all have signs on the ticket machines informing you that all journeys through the affected area have a 25% discount and you should buy at the ticket office...
... where you find it's not true at all, many of the flows are priced by XC and therefore zero discount is offered.
This really should be far more clearly advertised, it's currently very misleading. Basically, SOME of the walkup fares passing through Dawlish are discounted but the majority are not
Quite how your average customer is supposed to understand this and why it's an issue I've no idea. To most people, a ticket is a ticket and telling them that if they wish to travel from Newton Abbot to Hereford they can have 25% off but if they wish to travel from Newton Abbot to Worcester they cannot is downright confusing. XC are not offering Advance fares on many services so the 'offer' of only buying a ticket to/from Exeter is of no value. You are left with no choice but to pay full fare for a journey thats conducted mostly on a bus.
Even reasonable splits are out of the window as the buses are direct and do not call at intermediate points, therefore for some the cost of travel with XC during the disruption has actually gone UP.