Telkom *****ing from me

I took out a contract with telkom on the 20/03/2019 . In the contract it said there is a 7 day return. I did send telkom an e mail to cancel the contract and have been in contact with them . I also took the product back to telkom branch in northgate before the 7 days was over . Now today the 18/12/2020 a credit co phoned me for an amount that i need to pay . When i cancelled the contract it was siad that i do not have to pay anything i would like to know what the hell is going on with telkom . More than a year later they phoned me for money nobody from telkom ever phoned me . For anything i will be taking this further . I