unable to add funds to my account

Hello Toni.D, 

If you're having issues regarding iTunes & App Store you may follow these steps to resolve it.

https://support.apple.com/en-us/HT208687 <-- If you're not able to add funds to your account

if the issue persist,

https://support.apple.com/en-us/HT201232 <--- support phone numbers according to your region

https://support.apple.com/contact <--- you can chat with an Apple Care advisor as well

Regards.