Mark Fox review about company D & J Wolfenden Building & Roofing

I am just in the process of selling my property and found my windows have not been registered with fensa, I knew nothing of them until this point and I am having to pay myself for a certificate because D&J Wolfenden are now not answering the phone to me .They are not registered with fensa as advertised and do not get there work checked with building regulations. I paid £7,000 for the work on my property and they are refusing to pay £74.00 for my certificate.