Booking class on paid ticket not honoured.

I just booked using united.com a ticket YVR-HNL-LAX-YVR for december. They gave me a 600 plus fare and the YVR-HNL was in First (A). The rest was in T. The yvr-hnl leg was on Air Canada. AC says they have it as a tango fare or (their) A. Back and forth etc. etc. Finally spent 1.5 hours on the phone with the web people at united. (After 2 call to the phone reservation side). They said it was a mistake in the web and they could only rebook that leg in first (where I would have to pay the fare difference) and waive the change fee. That's it. They said I could file a complaint on united.com

I have screen shots of the purchase where it clearly says First (A) under that leg.

Do I have other options?

Thanks,

Lorna