Insurance issues

Me and my partner got married 2 weeks ago after been together for over 13 years and living together for 8 of those. We sold her old car roughly 2 months ago and didn't replace it straight away , her old policy ran out and now back from our honeymoon we have stared looking at replacements. She has a claim
And a driving conviction and with her maiden name getting quotes if around 6-700 pounds , change her name to her married name and change her status to married , it literally adds 500 pounds on that! We have tried comparison sites rang up to be told it should be cheaper , but when they get the quote back we have had 4 companies unable to give us a answer as to why ? Hopefully some insurance companies on here can shed some light , thanks