On Friday, 13 February 2015 06:28:12 UTC, Roland Perry wrote:

"If you touch in on a yellow card reader to make a journey and
then decide you don't want to make it or you can't because of
service disruption and touch out again to exit your Oyster card
will be charged. We apply charges to discourage fare evasion.
However, you may be able to get a refund if this happens."

The burden here is far too much on the innocent traveller.

My journey was different to that. It was, like the OP, ENTER at Victoria NR, then a minute or so later EXIT at Victoria NR, then a few minutes after that ENTER at Victoria and finally EXIT at Balham. In that case it is clear I could not have made 2 journeys so I suppose that's why I got an automatic refund.