Maybe... I would call again and explain that you were told by another agent that the ticket was invalid but that it still shows as live now in Manage Booking, so can they double check the status please. If they haven't taken any avios or cash it might turn out to be a bank error in your favour of course but I would expect it much more likely to be automatically cancelled at some point. You may want to ask them if they can process any outstanding payment over the phone. Check before calling for alternative timings with availability you could suggest if needed. Just assuming it's OK when there has been no payment and they have said your ticket is invalid seems somewhat risky to me.