Won’t let me make a repayment

[Mark26]

I had a plan for AirPods and when I open the app it shows my David’s plan and says I have an overdue payment and to make a payment so I press make a payment put in my billing address then it says the payment part at the bottom isn’t working and to get again later but it hasn’t worked all day

[MI5 · Accepted solution]

@Mark26 

You'll need to call customer service.
Numbers here Guide: Coronavirus Community Help and Support 
When it comes to the reason you are calling stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
Say "Upgrade", "Lost/Stolen" or "Fraud" if you have to, to get put through to someone.
8.00am is the best time to call if you can. 

Guide: How to Pay Your Bill (Airtime & Device Plans)