A friend of mine called to do a X TLV booking, rep told him that he can't book F even if F shows available, the guy told the rep that he is able to book F online, rep said it's a glitch in the system which is due to a system migration, and even if he has a ticket and ticket number, when he arrives at the checkin counter the rep won't issue a boarding pass if the passenger won't prove that he's a senator member.
I don't see how they could deny boarding if he has a ticket though