Debting my bank account without my permission

On thursday afternoon i have received an sms from MBD attorney stating that on the 25th of july they going to debt my bank account of the amount of R 2500.00. i am aware that i am in arrears due to the fact i was unemployed. But with no confirmation i feel that they don't have the permission to debt my account. My salary is only R 3500.00 per month and i wont be able to pay that amount all at once, i can only afford R 150.00 a month for now. I do not have no record of agreeing to that amount. I also have other responsibilities away from Foschini. I did contact them to explain my problem but they are transferring me to everyone else but no one is willing to assist me with problem. I also have a sick mum at home which i have to to for her medical treatment so i really can not afford to pay them all at once. Can you please help me with this matter as the 25th of July is just round the corner. This is the phone number i have received the call from ***