Happened to me twice recently on the £1 sellers fees offer.
First time, requested a call back and the nice lady explained the 30 day listing rule, but as it wasn't clear in the offer Terms & Conditions, I got the extra charges refunded (£5-ish).
I should have manually re-listed during the next offer, but didn't get round to it, so when the next item sold, and the changes came through (£6.90), I got in touch again. This time a not so nice man said 'tough' nothing he can do. I politely disagreed stating that it had been corrected before, and once he 'read my notes' came out with the 'you were told it was a one-time refund, so you don't get it again. This was not my recollection of the first conversation (one time refund was not mentioned), so asked to speak to someone in authority (which he didn't like, and said it would make no difference). I was told I'd get a ring back in 24-48hrs. 6 days later I requested another call back, and explained everything in detail, and got a full £6.90 refund (from another nice lady).
There was an option to list for 30 days under business tools, but I've just looked again to check this, and now there is only the 'Good 'til cancelled' option for fixed price, with the small print stating that there will be charges after 30 days. So it's a memory test to cancel and re-list manually.
You may be able to argue against the charges for a bit longer, but it looks like they have added the statement to avoid refunds on future listings.
Graeme.