Entering and leaving a station within a few moments
 

I entered Sudbury hill on the pic line. I realised that there were
severe delays from the announcement. By that time I had already
touched in.
I touched out within 30 seconds of touching in and thought nothing of
it.
The next day £4.20 was taken from my card sudbury hill- sudbury hill.
The guys at the window told me to call the oyster helpline. I was
advised that the credit would be put back on but I have to touch in
within 8 days at a certain station. I nominated kings cross, and was
told that I have to touch in at the piccadilly victoria line entrance
to get my credit back.

The whole system is a farce. On the print out from the ticket office
there is no sudbury hill- sudbury hill journey. It just says pre pay
exit sudbury hill. But at the ticket machine this is clearly visible.
What is going on?