Owed money by Damelin

I have run out of ideas on how to get someone from Damelin to respond to me. I enrolled to do a course with them towards the end of last year, paid my deposit and shortly thereafter received correspondence from them stating that they do not have course material available. They assured me that it would arrive, so I continued to pay my monthly instalments for around 5 months. There was still no material available so I requested a cancellation of the contract. The cancellation was granted and I was told I would be refunded in 90 days. 90 days have passed - I still have no refund and Damelin is now threatening to hand me over!!! They do not answer the phone so I cannot speak to anyone and they don't respond to my emails.