Penalty for late joining

In January I rejoined Discovery who imposed a 5% late joining fee. I submitted a declaration of previous membership on the 13 January - no response. I emailed them on the 3 and 13 February querying why I was still paying the penalty. No response. I phoned the call centre twice spoke to Selwyn ***) who said I should have a response in 24hrs - no response. Phoned again spoke to Iwazi ***) said I should have a response in 2 days - that was over 2 weeks ago - no response. I have emailed 3 complaints on their website where they promise a response in 24hrs- recd 1 missed call from Trish who said she would call me back - no call back to date but an email saying they could not contact me. What about an email saying they will sort out the problem -no. I have belonged to a Medical Aid my entire working life since 1985 including 9 years previously with Discovery. I am shocked at the complete lack of customer service I have received from Discovery. In total I have communicated with them 8 times and no one has attempted to resolve this issue yet they happily continue to deduct my monthly premiums. So now I have to resort to hellopeter - maybe Discovery will respond now?