Thanks everyone.
I am still waiting on it to arrive. I did send an email to Cartier with the serial number to see if they would check its authenticity this was the email I got back. I get they want people buying in stores but with a brand with such a long history and many vintage pieces at auctions I was surprised they would not advise if it was an authentic serial number. I am planning to take it in to be serviced when I get it and I did buy from Brandear using PayPal through Ebay and there is a 14 day return policy.
Thank you for expressing an interest in Cartier.
In response to your enquiry, we kindly inform you that Cartier does not offer an Authentication Service.
Cartier has chosen to sell its creations exclusively through its Boutiques, official E-boutique online and international network of authorised retailers (for watches and accessories).
Therefore to ensure that you are not disappointed, a list of all Cartier Boutiques and Cartier authorised retailers is available at https://www.en.cartier.com in the "Find a Boutique" If you purchased your creation from another source, regrettably we are unable to comment on your purchase or to provide you with any further information.
You can be assured of authenticity of Cartier creations, as all creations are accompanied by some form of certificate notifying the legitimate purchase.
Yours sincerely,