Hey, you can change your seats if you get the PNR from your travel agent yourself online, or ask the TA to change, if you prefer a Window. For a couple travelling together the center seats are nice because you can lower the divider and speak to one another while this isn't possible in the window seats. Unless you're hoping to have a bit of both of course, however CPT routes (and JNB) tend to be premium-heavy, and this time of year is especially heavy for travel to SA, so I doubt there'll be empty seats available.