Charge of $12.83.
I do not know why I am being charged $12.83. Please explain and tell me how to eliminate that and future charges.
Charge where? Very little info to know what or where this is coming from.
What is the charge for?
If it was something Mozilla related then perhaps you may have purchased a monthly subscription for Mozilla VPN. https://www.mozilla.org/products/vpn/ https://support.mozilla.org/en-US/kb/mozilla-vpn-faq
If the charge was indeed for a Mozilla VPN subscription that you purchased and change mind on and need more help that the above FAQ link does not answer, then you should post in the Mozilla VPN forum for it instead of here in the (desktop) Firefox forum.
To post a thread in Mozilla VPN section use https://support.mozilla.org/en-US/questions/new/firefox-private-network-vpn/form