MIA is correct. Also normally ony J and D get the VS promos. But if there is a Z fare available, take it and book your own limo (Volvo) as most times it is cheaper to do that and most of the time you do not use all the limos. J and D also allow for drive-thru check-in in London and JNB IIRC.

Also if you call and ask for a Z fare maybe first ask for "Zeee" or "Zulu" fares as asking for a "Zed" may confuse the agent as ZED fare are a whole different bag of tea that is only offered to a very select group that requires the most hard to get airline card. (Italicized text is a sorta directed joke)