Looks Like UA is competing for the business on April 15 or 16th departures (also see a may 26 departure) with $840-ish RTs:
Cost: $836.70
Miles: 21,230 total miles
CPM: 3.94 cpm
Houston (IAH) to Frankfurt (FRA) - Tue, Apr 16
United 968 Dep: 6:20PM Arr: 11:35AM
Layover in FRA Wed, Apr 17 10h 30m
United Frankfurt (FRA) to Johannesburg (JNB) - Wed, Apr 17
United 9138 Dep: 10:05PM Arr: 8:40AM
RETURN
Johannesburg (JNB) to Frankfurt (FRA) - Mon, Apr 22
United 9139 Dep: 7:05PM Arr: 5:45AM
Layover in FRA Tue, Apr 23 8h 5m
United Frankfurt (FRA) to Houston (IAH) - Tue, Apr 23
United 969 Dep: 1:50PM Arr: 6:10PM
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Read my blog for my journey to 1-K