Need urgent advice, My renewal date is 28/Feb, currently SL with 59,084 miles

I'm flying 26th Feb JNB to HKG in D which should earn me 8,288 miles and get me to GO but miles from the last flight won't count to the new year. I lost my GO in 2014/2015 because I was about the same amount short and just in case next years travel plans work out the same way, I don't want to be left without GO because of these 8k miles!

Is there any way to call CX to upgrade me to GO early (i.e. before my flight) so I can get the miles from the JNB-HKG for the next qualifying year.

I thought of another solution which is to do JNB-CPT-JNB on BA (but operated by Kulula) on the 26th morning before the CX flight for about US$500 but I'm not sure if BA flights operated by Kulala earn miles

Any suggestions would be very appreciated!