Retainer amount not informed about

My contract is expiring on 11april 2021. I went to a telkom store on the 25th of March to cancel. The consultant did not inform me that an amount of R945 will be charged. I was paying R70 for the contract. My reason for cancellation is affordability, now this R945 I cannot afford. Utterly dissapointed. Never doing anyt business with telkom EVER again. Called in to get assistance from customer care and was told I cannot be assisted....