Damelin refusing to cancel my contract even after explaining my condition

Good day I app**** for admission with Damelin correspondence school because at work I app**** for a bursary but unfortunately I didn't get it. In September 2019 I went to their branch in Pretoria to explain that firstly I can't afford to pay the montlhly fees because I pay R5000 for my 2 daughters fees and R1600 for their transport monthly and that I just bought a house and I pay R9000 monthly. So it will be difficult for me to pay. They advise me to write a cancelation request because I have valid reasons and my account should be terminated. On the 13th of September 2019 I sent an email to Damelin H. O for cancelation. They didn't respond and still debited my account. Now they sent me a letter of request which I don't understand why they did because they haven't responded to my email with reasons as to why my plea was not accepted. I am really financially burdened and I want to terminate the contract from September 2019.I have proof of all the accounts I am paying and proof of cancelation letter. Please don't put me deep in debts