Unauthorised and Invalid Insurance Cover active on Old Decoder

My mum only received sms this month indicating that she has taken insurance on her decoder. She was perplexed as we have not taken any insurance with MultiChoice for the decoders. Upon following up with MultiChoice Insurance we were informed that we have an insurance backdating to 19/02/2010 resulting in R2120 paid already. This was an old decoder that got damaged and was not claimed as we knew it was not insured. For more than 3 years we have been using two Explorer decoders and this is reflecting on MultiChoice system as well. So can we been billed for insurance of a decoder that is not operational on MultiChoice system. This is totally unacceptable that we have not had any insurance policies sent to us all this time and communication on insurance active on MultiChoice. We would like a refund of the premiums charged to us from the period the Old Decoder was inactive from MultiChoice system to current date or discuss with us on how to include current Explorer decoder in the cover backdated to when they were activated on MultiChoice. This is really exploitation and no monthly statements had been sent to my mum or communicated to us since inception of service. You are most welcomed to contact me (Son) on ********** as i manage my mum accounts.