Hi lexxm,
Thanks for reporting back the issue.
There was a configuration error with the new prices, that we have now fixed. There was no bug in the software, as calculation and price display (displayed and accepted at checkout) was correctly displaying the correct values configured, and the amount charged was also corresponding to configuration. Just the configuration was wrong.
We have of course refunded you the difference of EUR 5.25.
We have of course also fixed the configuration for the maintenance plan upgrades.
Sorry about that. It was my configuration mistake.