Thanks everyone. The outbound and inbound are both on BA metal so hopefully that means there is no issue. Any suggestions on when is usually a quieter time for the ticketing team if I were to call again? Or is that impossible to predict?!
Keep an eye on this forum! If there are umpteen cancellations, bad weather in the USA and baggage system has gone down, then calling about something in 2024 is obviously going to be an unhelpful moment. But yes, you can safely leave this until OLCI opens, you won't lose you seats or be bumped or whatever. If not on BA metal then that's different and you need to be on the case, since some airlines get fed up waiting for BA and just cancel things. Hence there is a special queue for those bookings, and some agents forget or don't know about it. But that's not the case here. Personally I'd make a note to check after Christmas before doing anything more but I know some people would find that difficult.