All the times and amounts are direct from the "Journey History" page of my Oyster Card account page on the Oyster Card website. I started the following journeys with £13.10 on my card ...
|17:13||Waterloo (Bkloo, Nthn, W&C Lines) Exit||£2.50||£11.60|
|17:40||Waterloo (Bkloo, Nthn, W&C Lines) Entry||£2.50||£9.10|
Note that there is a maximum fee of £4.00 GBP for a tube ride. The oyster system deducts the £4.00 when you start a journey and refunds the "change" when you exit (which makes sense to me). So the first trip has two entries: First I enter at Bank and get charged £4.00 GBP, then I exit at Waterloo and get £2.50GBP "change". All well and good. In total I paid £1.50 for the trip and we can see that the balance after that trip is £11.60 (£13.10 - £1.50). Perfect.
But look what happens on the return trip. I get charged £2.50 upon entry at Waterloo and another £4.00 on exit from Bank. I have been charged £6.50 for the return trip from Waterloo to Bank!
The same happened to Justina, but it was even worse for her. She had only £1.80 on her card for the return trip (which should have been enough) but she could not exit at Bank because the balance was deemed to be too low by the gate which was probably trying to take the additional £4.00 after the Waterloo gate had already taken £2.50. The really bad bit was the attitude and aggression of the staff at Bank station. Very nasty and they obviously believed that the Oyster Card was always right and hence that Justina was a fare dodger.
Looks like a serious bug in both the Oyster Card system and staff training. How good will the Oyster Card people be at fixing this? We'll see.
Update 1: Not a good start. The FAQ for Oyster says that in cases of overcharging the victim should call them on a number that earns them 3.5p per minute! So, Oyster rip you off on using their card and then they charge you as they (slooooowly, no doubt) try to resolve the problem by phone. I've sent in an email message instead which they promise they will get around to sometime over the next 7 working days. Thanks guys! Not.
Update 2: No response from Oyster at all. I'll send another message.