Internet disconnected for outstanding payments already made.

I'm very disappointed in Rain recently. I have been using their WiFi for 5 years now with no problems but recently but they have disconnected my internet due to outstanding payments which I had already made and shared the proof of payments for. I'm being billed currently having access to internet, how is that making sense?

I have been calling them but everyone is dropping their calls on me. I have requested an account statement and they are not sharing that. The feedback i get is that the billing department are working on it.