Unfair Treatment

My son has been on my medical aid with Momentum since 2005 however in February 2017 he started working and then moved onto his own medical aid with Discovery. Unfortunately he left his job and was then left without medical cover. In November 2017 I placed him back on my Momentum cover. About a month ago my son got involved with using recreational drugs and he didn't want it to become a problem so he came to me for help. I took him to our GP and she referred him to a clinic. When I approached Momentum for authorisation, I was told that because my son was on the policy for less than 12 months, they needed to do a clinical assessment. My GP then completed the required forms and sent it to them. On the forms she noted that in the past year my son was treated for Bronchitis, Pharyngitis and Soft Tissue injury to his shoulder. These issues that he was treated for has no relevance to his current situation with the drugs. They are also not pre-existing conditions that he is still being treated for. Today I was informed by Momentum that they are not going to cover my son for treatment at the clinic due to the fact that we did not disclose to them that he was treated for the conditions previously stated. They also want to terminate my sons cover and refund all the premiums that have been paid to them. I feel that this is totally unfair and that they are just looking for a way out of helping my son. I can understand it if my son was treated for drug abuse and we didn't disclose that to them however he was treated for conditions that most people suffer in winter etc. I am totally disappointed with the service from Momentum and the way we are being treated. My son needs help now, but I am being told that I have 30 days in which to appeal their decision.