I had exactly that problem last year, and when I rang they insisted that the 2 for one and car pass deal didn't exist. It took me a LOT of calls and agro to get what I ordered.
I even wrote to them afterwards and complained (and asked for compensation as I'd got about £30 of calls to their premium rate line on my bill). I also mentioned that it might help if they didn't send the tickets out just before the event as it didn't give much time to sort out mistakes - no reply ever came
This year I booked online so that at least I've got written evidence of what I booked. Just got the email to say the tickets have been dispatched so here's hoping...