Why don't you answer your phone?

Hello, I want to make a voluntary payment from overseas to my national insurance contributions for "payable gaps". but every time I call the centre and go through the steps, you hang up the call. How am I supposed to pay it if I can't call you? Could you not just allow me to make the payment online with my debit/credit card? You already show me how much money I owe for incomplete years, so why can't I just pay it with my card? It would just be much easier for everyone if I could do it like that.

Hi,
I am sorry for the problems you have experienced whilst trying to call the NI helpline. I can assure you that lines are open every weekday from 8am to 6pm.  
However in your case, this enquiry cannot be dealt with by telephone. 
As you wish to pay for a period during which you lived outside of the UK, we need to ascertain if you are eligible to pay and at what rate. 
This can only be done on receipt of a completed form CF83, which can be found on our website.
National Insurance and Apply to pay voluntary National Insurance contributions when abroad (CF83)
Thank you.