There's no checkout here on purpose. Pick a pack, message him, settle it however suits you — he adds the credits by hand, usually within fifteen minutes.
No. Nothing on this site can charge your card. There is no checkout, no card field anywhere in the database, and no payment processor — Jimmy settles every payment himself.
Pick a pack on the Credits page and press Ask Jimmy. That records a request — it does not take any money and it does not add any credits. You then settle it with him over WhatsApp however suits you, and he adds the credits to your balance by hand.
One thing: an advertiser's phone number. Nothing else on the site costs credits — browsing is free, and so is an introduction through Today's Collection. What a number costs is set per listing, so a credit has no fixed value in numbers.
Every listing carries its own price in credits, so there is no single answer. Jimmy sets it — an advertiser does not price themselves, and is never paid out of it. A new listing starts at the site-wide figure and stays there until he changes it. The Credits page reads the spread off the live listings and shows it beside each pack, because dividing a pack by one price answers a question nobody asked.