poor customer service

My Netstar account has been handed to them, they have a website where you can see the amount you owe and select payment options there. I choose to pay the account in full it redirects you to your app to pay and after I was done, I got the payment successful screen. that was on the 25th Feb 2026. they still have not closed the account instead they keep calling about intrest fee when i have paid up and sent them multiple proof of payment.