Need to fix an error in the PHP code in the resource booking schedule

Good afternoon.

Need a PHP developer.
It is necessary to fix the error in the PHP code in the schedule of booking resources on the site "1C-Bitrix".
And then maintain the site.
Then think over the integration of the 1C-Bitrix site and the Bitrix24 portal.

Details in the TK.

The developer level is average - Midl.
Please do not disturb the studios.