RwandAir flies from Brussels to Cape Town via its hub Kigali. Planes are brand new with IFE, and free WIFI. J fares are usually extremely attractive like €1200-1300 return
They run a promotion with generous luggage allowance of
3 pieces of 23kg in Eco, 4 pieces of 23kg in Business and 2 pieces of 32kg + 1 piece of 23kg in Premium Economy.
The promotion is for booking made until the 30th of November.
Alternatively extra luggage (23kg) costs only $115 for BRU-KGL-CPT or $8 per extra kg.
https://www.rwandair.com/baggage-cargo/