Thanks for the tip. When I'd tried the chat bot on the site before, it would just give me canned information and not connect me with an agent. You must have found the magic words. Meanwhile I'd followed the advice to message them on Twitter. It took 65 min. for them to respond (including time dealing with a bot that asked for information and then said it didn't understand despite my giving information in the format it requested)
and to get me an appropriate seat, but it is done! Thank-you all for your help.