Spark NZ are useless

I use the app to pay my bill. This means my debit card info is attached to the account and I just swipe away, I don’t put in any bank accounts or references. So how can my bill payment have gone missing?! It’s all automated through the app. I swiped to pay my bill and it took a while on the loading screen, but I saw that it had gone out of my bank so thought nothing of it. A week later I see that my spark bill hasn’t been paid! I called the bank to confirm and they gave me a reference number and a merchant number. It has 100% gone to Spark NZ. I have been on the phone twice to customer service reps who tell me they’re investigating. I have messaged through the app FOUR times. I repeat myself and they tell me the same thing. I have said I don’t want to be billed until my money is found, yet I have been charged another month, and this is leading to another month. If I want to cancel my account I have to wait 30 days, so that’s another bill. I have told them I do not trust them and will not pay until they find my first payment. How am I supposed to pay another bill without knowing it’s going to the right place?! They do not care about how frustrating this is and that this is going to affect my credit score.

I have no idea what else to do. I just want the money to be found! Where did it go?! WHY CANT THEY FIND THE PAYMENT? What the fuck CAN I DO at this point?