Arrears Account

I registered with Oxbridge Academy and was happy with the service I received from the beginning. However, in January 2014 I was accepted by UWC for a different course part time. I then contact Joseph at Oxbridge to inform him of this and he responded by sending me a cancellation form, which I completed and sent back. He never acknowledged receipt or anything.<br> <br> In September 2014 I received an SMS stating that I am in arrears and they are waiting for payment. I forwarded the cancellation form to them again and once again no response.<br> <br> Now, 01 June 2015, I received another SMS that I am in arrears. Can someone please assist? How many times must I send the cancellation form?