Hello,
The "Contact Customer Service" is controlled by (%PAGEHEADING%) macro (please refer to header.shtml template for further details). The (%PAGEHEADING%) macro allows dynamic headings depending on current page. To break the logic you must customize the TTXTicket.pm, look for the line that reads;
$data->{PAGEHEADING} = '[%Contact Customer Service%]';
Change to
$data->{PAGEHEADING} = '[%Help Desk%]';
I hope this helps...Arv