There is a problem in Matuikio regarding Extra Fees.
Lets say you have four extra fees in an event. In the sql they are labeled 1,2,3,4. Then if you delete the third event and they are now labeled: 0,1,3 it doesnt work, and you get this error: Extra fee with nr 3 not found!
The solution is to go into the back end of the sql and manually make sure that the extra fees are labeled sequentially with no gabs. 0,1,3 becomes 0,1,2
When the extra fees are labeled sequentially, and what was previous no 3 is now number 2 then everything works again.
I would love to see that fixed in an update. Thank you.