Poor client service

My Fedhealth membership was terminated on 28 Feb 2021. According to the scheme I still owed them money, which I already paid on 7 Jan due to my cancelation. On 16 April I received an email saying that I do not owe the scheme any money. Now, on 22 Oct I get another email claiming that I owe them money and further action will be taken if not paid. I am so disappointed, as this wasn't even my fault. I would definitely not recommend Fedhealth to anyone.