How to talk to someone on the phone about my issue

See >>> Change, add, or remove Apple ID payment methods - Apple Support

If you only have a single Credit Card set-up for your AppleID account, you will need to add a new Credit Card to your AppleID account - after which you will be able to delete the old card details. 

It is often a good idea to have two (or more) payment cards associated with your account - as, in case there is a problem with your primary card, a charge can be made to the second card without risk of impacting ongoing access to your AppleID account or associated services and subscriptions. With multiple Credit Cards, you can choose the sequence in which card payments are made.

You may find these support pages to be helpful:

If you need to change or update your Apple ID payment method - Apple Support

Add a payment method to your Apple ID - Apple Support

Remove a payment method from your Apple ID - Apple Support

Payment methods that you can use with your Apple ID - Apple Support

Assuming that your payment card is supported, if you cannot resolve the problem yourself, you would be best advised to seek assistance directly from Apple Support:

Official Apple Support

You can also initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

There was a purchase made on my debit card that I have no Knowledge of. And I would like to speak to someone about it.