R4489.00 deducted in my bank account

Today around 18h58 I receive an SMS from my bank that debit order of R4;489.00 was deducted by disc prembbut I am surprised as I no longer with discovery, I was retrenched 2015 in March and my medical aid was terminated. And was told to R2;400.00 that discovery paid on my behalf and in June that what I did that money was paid and the lady by the name of Kaya confirmed that the money was received.. I was not gonna managed to pay the money that they want as I am unemployed.but today I got the msg that they deduct the money from my account that I don't know, I immediately called call center the guy told me that o don't have an outstanding amount.. But I mist write the letter to discovery and explain that there was a transaction on my account. Why must I beg my money I am now at polmed I believe no one is allowed to have more than one medical aid but 4489.00is out in my bank account, I really need your help I am not working..I cannot to effort to loose 4489.00 that I don't know what is that for.