On Wed, 11 Oct 2006 09:56:41 +0100, Ken Welsby wrote:

If the answer is surrender for refund and re-buy, what's the penalty
likely to be? I've been rummaging around the web without finding an
answer

If you've used it for (say) 2.3 months, you get refunded the cost of
the ticket less 2.3 times the cost of a monthly season.

If you've used it for less than a month, however, you get charged for
weeklies instead (I'm not sure of the exact method of calculation).

There may be a £5/£10 administrative charge on top.