I see your message was posted four years ago so I hope you're still searching for news about the Excello. Hope this helps:
The survivors of the Excello were located by members of 44 Air School (Grahamstown) and then again by members of 42 Air School (Port Elizabeth) who diverted the hospital ship "Atlantis" to go to their assistance.
At 12:38 hours on November 20, 1942, Anson number 3279, piloted by Lt Clegg with crewmen Lac Bryant, Lac Hetherington and A/C Cowall spotted a lifeboat with seven occupants, red sails and four oars drifting in the Indian Ocean at position 34° 08' S 26° 17' E (about 20km south of Bird Island).
They dropped rations, water and a message reading: "Help is coming".
The Air Schools were part of the joint South African Air Force / Royal Air Force Joint Air Training Scheme during WW2.