I've worked out that the difference they're quoting is due to the fact that I had to split myself off the PNR, and as a result they are re-pricing based on the new reward table when the booking was made months ago - and it's not due to an increase in distance band, but I haven't been able to communicate this so far.
So far I've been told:
- You should pay more because it's an additional flight (never mind that the 30,100 they're asking for costs more than the flight itself outright)
- Connections overnight are stopovers
- Connections >8h are stopovers
- Points re-pricing is based on original ticket issuance date
Will try to call again later, but losing patience given that the last two times it's already been HBA picking up.