Threats of blacklisting because Discovery staff not doing their work

I recently started working with my old employer again. Who also has the staff on Discovery and uses a broker to handle all medical issues. I was given a form to complete for membership application to discovery. I assumed my current discovery membership would be carried into the new job. Much to my surpise I get a nasty email stating I owed Discovery R3300 - I contacted them and was told my membership was cancelled and i got a new membership. I asked why as I clearly stated on my application form I wanted to stay on the same plan. The lady from doscivery said there was enough time before the inception of the new membership in 1 April and I could complete a transfer form which she sent me and the company HR returned to her. Funny thing is I get a nasty sms today telling me I am going to be blacklisted for their ***** up. They were supposed to correct the cancellation and do the company transfer. I am NOT accepting this mistake on their part and if I have to will contact my cousin who is an attorney to assist in this matter or I still have the CEO and other top management's contact details from a previous issue I had with Discovery staff *****ing up and will gladly contact them again to assist. Discovery really sucks when it comes to doing due diligence and have their staff do fulfill their promises.