We need to know which quests you did, that rewarded you with Sanctum coins. I remember an old report with another person having this issue but we fixed that, so there must've been more than one quest rewarding the wrong coins.

The issue lies in the quest system. This quest is available for both factions, but usually only Elyos do it. That's why the reward are Sanctum Bronze Coins. We currently have no way to set faction specific rewards, so a fix won't come soon as this bug has no priority.

Edit: After further investigation we found out that this is a bug from NCSoft. The quest rewarded you with faction independent scrolls in an earlier Aion version. In this version the rewards changed to Elyos coins, even though still both factions can accept this quest. There's not much we can do about it. Quests are officially not supposed to reward different item IDs per faction, so we won't alter the system just for this one quest. As we don't have a "Won't fix" label, I set this topic's label to "No bug".