wp-cron.php overloading problems

My ISP suspended one of my sub-domains due to the above, and directed me to a recommended fix. This was to enter the following 2 lines into wp-config.php and add a cron job
//Disable internal Wp-Cron function
define(‘DISABLE_WP_CRON’, true);

wget https://www.yourwebsite.com/wp-cron.php > /dev/null 2>&1

I now have the following errors;
//Disable internal Wp-Cron function define(‘Disable_WP_CRON’, true);
Warning: session_start() [function.session-start]: Cannot send session cookie – headers already sent by (output started at /home/spider/public_html/ipad/wp-config.php:3) in /home/spider/public_html/ipad/wp-content/plugins/easy-contact/econtact.php on line 112

Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at /home/spider/public_html/ipad/wp-config.php:3) in /home/spider/public_html/ipad/wp-content/plugins/easy-contact/econtact.php on line 112

Warning: Cannot modify header information – headers already sent by (output started at /home/spider/public_html/ipad/wp-config.php:3) in /home/spider/public_html/ipad/wp-includes/pluggable.php on line 881

When I remove the 2 lines from the wp-config.php file (on a different sub-domain with the same problem) and remove the cron job, I got the following error;
Fatal error: Call to undefined function wp_is_mobile() in /home/spider/public_html/tattoodesigner/wp-login.php on line 67

I seem to be stumbling from one problem to another and definitely need help

Regards
Margaret