Contact form stopped working

Get error message when completing the form and by reading threads it may relate to spam as the error message box is bordered with orange. Had this form working for 3 years and in the last week, it seems to have decided to stop working properly. Been playing with it today and looking over our recaptcha plugin but have not been able to resolve the issue with the Contact form 7. Our host advises to change plugins. I’d prefer to try and solve the issue. Any help please

The page I need help with: [log in to see the link]