We’re sorry to hear about your experience, and we appreciate you taking the time to share your feedback.
Our plugin does not modify any order data unexpectedly — it only performs combinations or merges according to the specific options selected by the user. If something went wrong with tax calculation, we’d be happy to review your exact scenario and help you identify the cause (it may depend on your store’s tax configuration or other active extensions).
Regarding the premium version, the upgrade is completely optional — all the main features work in the free version. The paid version simply adds automation and advanced controls for users who need them.
We genuinely value all feedback and always aim to improve. If you’d like, please contact us through the support forum so we can reproduce your case and resolve it for you quickly.