Payment not made to municipality

I paid my municipal bill via the APP on 22 Nov. Now I received a final demand from the municipality. Feedback from Easypay has been that they would do the payment - so they had the money all along? Still waiting for the proof of payment and have now been charged arrears fees as well. Very little urgency to resolve the issue and would seem that financial management is poor as why didnt you pick up that there were payments in your account that werent paid over? I would like this resolved asap by getting proof that payment has been made, Easypay notify the municipality that it was their error and Easypay paying the arrears fees.