Vodafone Illegally Converted My Postpaid to Prepaid Without Consent

Vodafone changed my postpaid line to prepaid without my consent. I had intended to terminate my contract a day before it was scheduled to end on August 6, so it was a bit shocking for me to see this change. To ensure a smooth process, I made an early call to the customer service representative. They assured me that they would forward my request to the expert team, who would then contact me to convert my line accordingly. No one reached out, and out of the blue on July 24th, they switched my plan to prepaid and billed me for an entire month. I refuse to forgive them. I'm disappointed with my experience using Vodafone for nearly 15 years. Unfortunately, I never found satisfaction with their service.