can I receive a refund if I cancel the service before the end of the paid month?

For mobile plans, if you cancel within the first 15 days (trial period), you may be eligible for a refund.
See point 4 here for more details: https://fizz.ca/en/faq/unsubscribe

For home internet:
1. If you cancel your Home Internet services agreement during a payment cycle, you will receive a prorated refund based on the remaining days for the monthly fee paid at the beginning of your payment cycle (excluding any additional data blocks).
2. This prorated refund will be processed once your Wi-Fi modem has been received by Fizz. Based on the date at which you return your modem, expect a delay of approximately 4 to 6 weeks before receiving your refund.
More info here: https://fizz.ca/en/faq/how-do-i-unsubscribe-from-fizz-home-internet

If you have any questions for Fizz, you can Live chat with Fizz support from 8 AM to 9 PM every day:

1- Connect to your Fizz account by clicking « Login » in the top right corner at fizz.ca
2- Any ad blockers in your browser should be disabled.
3- open one of the help links mentioned above from Fizz Solution Hub
4- The green chat bubble should appear after a few seconds in the bottom right corner.

Hi Fabio

Sorry to hear Fizz mobile did not meet your needs or expectations.
Was there any specific issue?

If you cancel during the trial period, you should be entitled to a full refund of the plan fee: https://fizz.ca/en/faq/unsubscribe