Payment correction due to an operational issue

A couple weeks ago I received an email from TFL (Transport for London) about a payment correction. It read as follows:

Fantastic, or so I thought, TFL are taking responsibility for some problem (which to be honest I’m not sure I’m even aware of) but I suspect it was something to do with some of the tube lines being out of sync or out of action that day. Except today I received another email from TFL, this time letting me know I’ve not collected the refund they authorised and telling me how to re-arrange collection. So, in theory this is good news, but I wasn’t aware there was a time limit on the first email, I’m not sure whether there is a time limit on the second, more importantly I don’t see why TFL can’t just apply the credit to my account without me needing to ‘collect’ it.

They should have enough data about my travel habits to spot that I don’t live in London, or to at least realise that I don’t regularly use the tube, even if I frequently do. They have enough data to know I’d only visited that actual tube station twice in the last year, they should know the station I visit most regularly is Paddington, and I would have thought that all of this is irrelevant and they could apply it remotely.

Anyhow, I’m just interested if anyone knows more about what they can or can’t do and/or what they choose to do and/or whether these corrections expire at all? As someone who doesn’t live in London but has been regularly using the tube for years, the idea of a refund is so novel I don’t want to waste it! Any ideas?