Been trying to book a guest pass for the members area for Wednesday/Thursday for the past week, but the website will only sell them with a members pass for the same days. As I already have a pass for the week I was fearing the worst and resigned myself to an ACO rip off of some sort. Anyway, emailed this morning, was called back within the hour, and as I already had a full week pass, I was able to buy a full week guest pass despite them being shown as sold out on the members website.
I have to say well done ACO for excellent customer service.
FYI I was told that the Wednesday/Thursday passes will not be valid on the Friday.