Ajax problem on one host

Hi,

I have some ajax scripts that call php pages and I have a simple response depending on the reults of the PHP script.

Reponses being like:
If an error in the php it responds:
echo $_GET["jsoncall"].'({"response":9})';
If all OK it responds:
echo $_GET["jsoncall"].'({"response":2})';

This all works fine on three hosts but on one I have a problem that the response doesn't get processed as it prepends the domain name to the response like:

WhocanhelpmejQuery111208119818157206108_1479207010168({"response":2})

On the other 3 hosts I get the expected response which is:
jQuery111208119818157206108_1479207010168({"response":2})

Any ideas on how I can stop the Whocanhelpme (part of the domain name) being pre-pended please.

regards
Steve