Mango - Seat advice
Having just flown this airline (CPT-JNB), thought I'd put in some info for the benefit of others.
Mango is a LCC that has certain code-shares with South African. I.e., you can book certain Mango flights as part of an SAA trip (which is what I did). Doing so gets you some modest benefits, including a ZAR70 allowance for food/beverage (which otherwise are charged).
All planes are 737-800s, with 186 seats (3x3). Exit rows are 15 and 16, which have some additional legroom (row 15 appeared to have a bit more). No seats recline, so you don't sacrifice this feature in an exit row (or row 14). Row 11 has no windows, although you can see forward somewhat via a window that's even with the seats in Row 10.