I need help in canceling mytechzone debit order

To whom it may concern , I would like to file a complaint against Mytechzone company This week I received a call from mytechzone company firstly they ask to offer me the cellphone contract but then they said they have to check whether I qualify for any cellphone contract.And that was when I gave them my information,the bank account ,ID number and my names unknowingly that they are going to use my information to open debit order of R140 monthly. I went to my bank branch to ask them to cancel the debit order they said I must contact the mytechzone company and ask them to cancel debit order I did so ,I tried contacting them it seems like they blocked me i also tried to send them an email , the email was also blocked