Contact Page – Confirmed Message Sent No Displaying

Hello WordPress & Forum Memebers,

I am currently experience a problem which seems to have occurred for unknown reasons.

On the contact page http://www.radarsdirect.com.au/contact
if someone puts in their details and click’s submit. A small loading sign appears near the submit button but nothing else happens after this.

The message is sent successfully, except the user has no way of knowing if the message they tried to submit was actually sent.

It used to work but now it doesnt. The people who designed it for me refuse to fix this.

Any suggestions appreciated, I can provide any further details of ym wordpress if needed.

Thank you very much