If it helps, the obvious re-booking would be BA59 tomorrow 2140-1010 (the same times as today's flight).
Otherwise, tomorrow there's BA55 to JNB 1905-0705, which would connect to BA6413 0925-1135 or BA6409 1035-1245; and then BA57 to JNB 2125-0915 connecting to BA6417 1240-1450 or BA6419 1400-1610.