Worst service ever

I changed medical aids in July 2014 from Discovery to a cheaper medical aid due to financial reasons and gave Discovery 1 month's notice as required. In November 2014 I received a letter from Discovery informing me that I still owe them R 5 000 due to late claims which I paid again and sent proof of payment through (AND I HAD ALMOST R 10 000 in my MSA!) . Then in Jan 2015 AGAIN I get email and sms from Discovery stating that I STILL owe them R 880. I logged a query (with reference numbers) online AND phoned twice where I had to hold while they investigated until the phone cut out. Today 11/02/2015 I get an sms from SSDA (collections agency) that Discovery has handed me over. Phoning THEM is even worse! The lady told me that she can't help me and if I do not pay they are going to blacklist me! I am cancelling all my life policies and credit cards that I have with Discovery as I am absolutely disgusted and disappointed in this company! I WILL NOT ADVICE ANY ONE TO HAVE ANY DEALINGS WITH THIS COMPANY EVER IN MY LIFE AGAIN