Chasing sales and money zero care for the customer

The sales rep came into my house sold their product, informed me that I will have one month free as they were running a special. I was not happy with the service and asked to cancel . Later on they tele service stuff started calling me , telling me I owe them money, I explain my situation, I then requested a copy of my contract as I don't remember signing one , to my surprise there's no initials to the contract as required by contractual obligations. They started calling me constantly informing me that I owe and I should pay R 1200 for that month I used their product and return their product, which I did . A month later debt collectors(vericred )starting calling me while I was under the impression that issue was settled. I eventually gave in because it was causing me mental distress . I was now charged for asking a statement just to see the amount they say I owe and all their calls . I've been making monthly payments no statement issued only an sms showing an amount