Payflex ****

I made a transaction with payflex on June 2025 in which I had to make a second installment onthe following month of July to which I did make the payment 2 days in advance , money was taken out of my account by payflex but payflex has refused to contact me to acknowledge payment instead they've been billing me for non payment , even after I sent a dozen emails pleading my payment that I made and even sending a proof of payment but still I'm being billed and when I call them they do not answer nor email me back , I demand to know what's payflex's standard of customer care, is this it? Is this how a business that does not charge extra fees make money? By reaping people off and by accusing then of non payment while they did pay. I'm never using payflex again, I would just like to make what I owe and delete my account with them. Please help.