Zip card transfers are NOT automatic

Ringading007

Just talked to Transport for London to request a transfer of the balance from my son's (Oyster) Zip card, as he's moved from the 11-15 one to a 16+. Whilst sorting this out, the helpful operator noted that he had 2 previous cards (he lost one ages ago) - BOTH of which had a balance on them.  It looks like you have to actively request a balance transfer - it doesn't automatically happen if they replace the card.  I'm wondering how many untold millions of pounds are sitting on lost/replaced kids' Zip cards??  Anyone else experienced this?  (I think the kind & helpful operator has just saved me a ton of my own money....!)