Health Care denied because of UK private pension

I have a Carta Sanitaria which expires in 2013 but my entitlement to healthcare has been suspended because I have a private pension paid in the UK.  The local ASL tell me I need a modulo (form) S1 from the UK to declare my pension and to declare that I do not receive a pension in Italy.  I have absolutely no idea what this form is or where to get it.  Has anyone else had this experience?