Getting onto an earlier flight (booked flexible J)
We booked flexible / premium J on SA7109 JNB-MRU dep JNB at 13:35, ticket issued by SA (flight operated by air Mauritius). We are arriving on BA55 at 07:10 (British Airways won't check out bags through since travelling on two different tickets) - if we are on time and clear immigration/ customs reasonably fast, how sympathetic are SA going to be to rebooking/allowing us to travel on SA190 which departs at 09.40?