I have an Economy Class V flight booked with Air Canada from San Salvador to London. The leg from San Salvador to Toronto is a codeshare with Avianca and Toronto to London is operatded by Air Canada. I'm trying to book seats in advance and determine luggage allowance and pay for luggage if I need to for the first leg. The problem is Avianca say it's Air Canada and vice versa. When I enter the PNR (same for both) each airline website page directs me to the other and I'm going round in circles! Both have been equally as useless on social media contact.

I'm worried I'll turn up for the first leg and be hit with baggage fees for my hold luggage if it isn't included in the first leg and there seems to be no way to manage my booking for the first flight. Has anyone managed to overcome this?