Error correction on the site, javascript, does not send a request

Good afternoon.

I am looking for a person, in javascript, while to correct a small error, then perhaps to continue the project and for long-term cooperation.

https://myheart.skillmi.ru/ - on the land, in the block with payment, when putting a name and a mail, a payment card should appear.
Previously, everything was OK, everything worked, but I had to connect the option for tax and apparently the setting in the payment itself was confused and now it does not appear on the land itself.

We need a developer who could fix this problem and everything would work correctly.
The ability to work with payments is desirable.

The price is negotiated.