@CW89 not sure if you are reading the updated info off the server. The new My Account has serious issue with cached page.
First ,login to My Account using Incognito mode. Check Payment History to see if it shows you having charged twice. Also, make sure you aware the fact that if you click "Change plan now" when you change plan, it will start the new plan immediately and charge you new plan charge, that might have led to the double charge issue
Gather the info from Payment history, then open ticket with PM support and discuss with them. See what can they do if you really got double charged:
1. If you have access to My account: At https://publicmobile.ca/chatbot.
Start by typing "Submit a ticket", then click "Contact Us", Then click "Other", then click "Click here to submit a ticket ↗"
2. If you don't have access to My Account or have trouble with Chatbot: Private message CS Agent at:
https://productioncommunity.publicmobile.ca/t5/notes/composepage/note-to-user-id/22437
**Monitor your Community inbox (envelope icon on the top right) after the ticket is opened. CS Agent will reply to you there