Account in arrears even after payment was made

Since both your chat functionality and e-mail options are not available and since my conversation with a call centre agent proved unhelpful, I'm resorting to HP.

I fully admit that my debit order payment did not go through, due to the lack of funds, but I did make a payment on 1 March 2019 to settle the outstanding amount. My attempts since then to change my "arrears" status have proved fruitless. I've tried to do it on my account (which you so vigorously promote while waiting to speak with someone), but I keep getting errors. I then tried to confirm the payment by dialling the number given and entering the amount when prompted. No joy. Then I spoke with a call centre agent to declare my payment and he acknowledged that you did receive my payment, but now it seems my arrears status will remain until my next debit order??? How is that acceptable?

I wish to get a settlement quotation from you because I am in the process of consolidating my debt, but I can't get one because my account is supposedly in arrears even though I did make a payment and you have acknowledged as much!

I honestly don't want to switch providers, but I'm pretty fed up with how difficult you make it for your clients to manage their own contracts.

Sort this out. Please.