Pre-booked seats changed

I have lodged a grievance against Kulula on 4 October after making a booking on 27 June for the purpose of booking preferred seats in advance. On arrival 2 October, at the boarding gate, Kulula allocated different seats to me and my family without my consent or any compensation. The seats allocated were against the toilet facilities on the plane which caused for a very unpleasant experience. After I insisted on a full refund for the tickets I booked 4 months in advance I received vague feedback (9 Oct) where Mr Twala-Mdaka first apologized for changing the seats and in the same email said they have no record of our seats being changed? I sent him all the proof and asked what the reason was for the seat change as he could not verify this. Until now I received 2 automated responses only. Since 9 October I received no refund or explanation why the pre-booked seats were given to other people. Kulula also has utterly bad administration if they do not know which passengers were seated in which seats (according to Mr Twala-Mdaka no changes were made) – this is not only appalling but frightening as I am sure that this is against safety regulations. I demand answers and compensation.