Thanks for all the feedback, in the end our bags missed the connecting flight at JNB to Windhoek . We had to run to make it as our BA flight was delayed due to not being on stand in time at LHR after maintenance . We did not have to go to Terminal B for the connecting flight to Windhoek, for some reason it departed from A with a Bus transfer to the aircraft.
I had Apple air tags which did help with tracking our luggage until it caught up with us 4 days later. Luckily we had packed with this in mind .
I did have a problem describing the luggage type, size markings etc to the staff at Windhoek so in future will take a photo of it.