Upsell Subscription Upgrade

Hey everyone!

I’m trying to implement a subscription upgrade flow and I’ve figured out most of it, but I’m stuck on one specific part.

Here’s my scenario:

  • Customer purchases a 30-Day Subscription at $59.99/month at checkout (using Funnelish Pay)
  • On the upsell page, they are offered an upgrade to a Quarterly plan at $149.99/quarter
  • I’ve set the upsell product as a subscription with a Trial Price of $90.00 for the first 90 days, then $149.99/quarter recurring — this part works perfectly

The part I’m stuck on: when the customer accepts the upsell, how do I automatically cancel their original $59.99/month subscription so they aren’t double-charged?

Has anyone solved this? Would love to hear how you handled it. Thanks!