I've never found the right tea leaves. Most of them were to bitter and some had just a totally different profile than the original clubmate. How close are the ones you are using?

For me using the cold brew method instead of cooking the leaves had the biggest effect on the bitterness.

The taste goes in the direction of ClubMate, but has a stronger tea taste than the original ClubMate. I think reasons for that are the reduced amount of sugar and the fact that ClubMate uses natural flavor in their tea extract.