Seeking advice! I've booked return direct flights to Canada via Opodo - both flights are Virgin Atlantic but operated by WestJet.

I can log-in to Virgin Atlantic's website to see my flight details with the information Opodo have given me, however, when it comes to choosing seats it says this is only available via WestJet.

My log in details do not work on WestJet - they require a 6 digit reservation code and my Virgin one has letters in.

Has anyone had this happen before? How do I get around it? I have a joint condition so I really really need to book an extra legroom seat. I've even tried contacting the assistance team at WestJet but keep getting told to call a Canadian number which I cannot do.

Any advice welcome!! Starting to get nervous as my flight is on Tuesday next week.

Thanks in advance