Cancellation of registration

Early this year I had registered for a distant learning programme with a school called Mancosa from SA. They delayed to register me and when they did. I couldn't do the program I paid my registration fee in December 2016. They only registered me in March.So i cancelled it with in there stipulated 14day period I filled in a form which I scanned and sent them. I called a week after I didn't get a response and I was told that the person responsible had gone on leave.i called two weeks later after several emails were sent and they said the papers were sent to Durban. I kept writing when they bill me no one responded to me now this is from March this year. Yesterday I received a letter of demand saying they will take legal action against me. I asked someone to call but they said that I am still liable to pay. The form I had sent to the school said whether they reject or accept my cancellation they would get back to me. Now why am i being sent letters of demands why must i pay even when I cancelled in time and why no one ever got back to me even after the numerous emails I sent them