There is a report error button on the register which you can use to initiate contact with the Insolvency Service. They will respond by email asking you to send a copy of the completion certificate, if they can't find it doen the back of a filing cabinet.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk