In message , at 10:31:05 on Sat, 25 Feb
2017, tim... remarked:

If you used Auto Top-up, you wouldn't have that problem.

I don't use Oyster enough to justify lending TfL so much money.

me neither

the auto-top-up that works for me is

5 pounds added when it goes below 5 pounds

Only £20 or £40 is available currently, and the trigger is £10.
--
Roland Perry