That's a very interesting figure
@SouthernOne, I wonder how it stacks up against others in the area? If it were to stand out as an obvious fare/revenue trap by SWR then it may be worth our while getting in touch with the MP for the area to bring it to their attention (or perhaps I'm being naïve).
Anyway, I heard back from SWR and they agreed it was in everyone's interest for a settlement to be reached. £120 admin fee plus the full Paddington to Ascot fare, with instructions to get in touch with TfL for a refund from the contactless travel. Ah well!
Grateful for everyone's help here and glad to have seen the back of this episode; lesson learned via the wallet on this occasion.