I have a 3 month season ticket between two stations and, say, make one return journey each weekday. If the train I regularly get home is cancelled, on multiple occasions, how do I claim a delay repay type of refund? On occasion the train cancellation has resulted in my travelling home by bus at additional cost. Is that claimable?
It's important to distinguish between Delay Repay and refunds, though sadly the TOCs don't exactly help matters as a lot of their staff confuse the two in their announcemetns and information to passengers.
Delay Repay is a compensation scheme for when you travel but are delayed in arriving at your destination. You claim this by submitting a form (most easily online) to the operator that caused your journey to become delayed. In the case of a season ticket, a fraction of the cost is taken (based on how long it is valid) to work out what each journey is 'worth'. A percentage factor is then applied based on how delayed you were. Not all operators offer the same level of Delay Repay, so check the relevant operator's website for exact details.
A refund is what you'd apply for if you wanted to return your season ticket as you no longer wanted it. In rare cases you might also ask for a partial refund for the pro-rata value of a day's travel if there was serious disruption and thus you didn't travel on that day. Rather confusingly, operators often ask you to claim this using their Delay Repay form, albeit giving the reason 'did not travel' or similar to distinguish it from a claim for if you did travel.
Whether or not you can claim for the cost of a bus ticket will depend on the reason why and circumstances in which you took it. Could you provide more details?