Agreed. End codeshares now!
If only it were that simple! I just had a completely different experience on an LH-operated ACcodeshare.
I'm flying YYC-FRA-TLS and back in a few weeks. Tickets booked through AC. TLS flights are AC codeshare. Wanted to select my seats. No problem on the AC-operated flights on AC.com. Couldn't select them on the TLS flights. So I call AC to get the LH booking reference. They don't have it. So I call LH, give them the ticket number, they give me the booking reference. I decide to just take that to their website rather than having them do it on the phone, so that I can check out all the inventory.
Of course, on the LH website, I can select seats for the AC-operated flights, but not the LH ones!
So, I call LH back. Guy spends forever trying to figure it out, eventually gives up, says I should call AC because it's an AC codeshare, he can't do anything, and if AC can't do it, I'll just have to do it at the airport when I check in.
Call AC again. They can't pull up a seat map because it's operated by LH. But they can request a specific seat fro the system and it will either accept or reject. So, using the LH website as though I'm just booking a new ticket on those flights, I find the seatmap and tell her what to query. Both accepted, all good now.
But what a nightmare, all because it's a codeshare flight.
