My horror story of RTW change at checkin counter.
my RTW was
---CDG-xLHR-DXB-xLHR-JNB-....
At BA checkin counter in CDG, I asked an agent changing ealier flight.
The agent casually changed my flight.
A few days later, at BA DXB checkin counter, an agent said 'You don't have reservation for DXB-LHR'.
BA cancelled my DXB-xLHR-JNB flights because of no show of the ORIGIANL CDG-LHR flight !!
You had better not expect propoer reissue and ticketing of RTW at an airport counter.