SUSPENSION OF MEDICAL AID

I am with Fedhealth from the 1st April 2013. Everything was going smooth until the middle of August when I received a sms on the 14th August 2015 telling me that I owe an amount of R 1908.00. In December 2014 I contacted Fedhealth to find out the correct contribution for the new year and they confirmed that it will be R 1564.00. I paid that up to now and I have never received any correspondence from them to say that my monthly contribution is increasing with almost a R 1000.00 in less than 6 months. My contribution increased from R 1055.00 a month to R 1564.00 from last year December 2014 to January 2015 and I accepted that. Suddenly I received a sms to say that I am in arrears with R 1908.00 on the 14th August 2015 and that my instalment has increased to R 1960.00 per month (with no documentation to prove that). I have not signed anything, nor receiving anything. In less than 6 months, my contribution increased with R 905.00. Now they want to cancel my medical aid because of the arrears and I didn't even get any notification. I spoke to Prudence Mota on the 20th August 2015 which she confirmed that I haven't received anything from them. Now im in arrears of R 3868.00. Im not happy