Inaccurate billing/badgering of client

Account suspended owing to poor payment according to supplier. No invoices sent out to client after suspension, no service was supp**** either, only letters of demand sent with an amount outstanding. When asked for a statement once again a letter was sent indicating an amount which was not correct according to my records. After asking for a statement again, a corrected one was supp**** at the beginning of February showing an amount of R180.88 being outstanding. This was paid on the 9th Feb.On the 17th Feb I received an email ( Final Warning) informing that I have an amount of R362.26 outstanding on the account. Certain consequences of non-payment were highlighted in this communication.Once again I have to react to a threatening letter demanding money but no proof of what has been received on a statement. I am tired of the badgering I have been subjected to by this corporation.I have been a loyal client for quite some years and am disappointed in the way this has worked out. Receiving automatically generated emails to which one cannot reply is a great frustration.