Kaching Bundles App & Upsells

The app is nice and it's well done, nothing to say on how it works, but my 2 stars is because i think the app is quite expensive and also because i didn't increase AOV with this APP. So, i think their pricing plan should be based on the real AOV they bring to the store instead of make pay on what ?
They developed to increase AOV, so let us pay for that if it does, because for sure in some cases it does the job, but in my case it didn't.