Best way to update channels?

I’ve been running Krypton with a Mediaportal backend for about 6 months, and the time has come to re-tune to pick up some new channels and remove some that have stopped broadcasting. I’ve tried just re-scanning in the Mediaportal setup program, but that has caused several issues within the Kodi EPG.
Some channels are duplicated with the same EPG info. Some are duplicated with no EPG info. Some should be gone but are still in the EPG.
Is there a better way to do what I’m after? I thought about just deleting everything and starting fresh, but the EPG info takes several hours to fill itself back in after a clean scan.
Surely there’s a better way?

Cheers in advance.

John.