Final demand letter on levies not in arrears!

Our complex, Stelway, Eldoraigne, has been doing business with Proadmin since May 2019. It has been a DISASTER from the word go! I am the owner of Nr 14. I pay my levies, with a Debit Order, with an amount MORE that the levy amount, on 15th of every month. My levy account is in Credit for more than half of every month, because I pay more that I am supposed to pay.. I have been paying my levies in this manner for 12 years. This morning, I received a FINAL DEMAND for ARREARS Levies, with a threat of 21% interest charged to my account. I am a bad payer? NO phone call? No sms? This company is just pathetic with their Admin, which is all they are supposed to do! Go after bad payers please! Concentrate!!!!