Nationwide Mortgage & New Build

Hi all

I've received my Nationwide Mortgage offer and thought all was going well until I found out that my conveyancer has to inform Nationwide about any builder incentives and get their approval before we can proceed.

I'm not expecting any issues over some lawn and carpets although I am part-exchanging which does have to be declared. How long does it take for Nationwide to approve the new build incentive form? It was submitted on 27 November and it has been chased several times.

Here's the form for those unaware: http://www.cml.org.uk/cml/handbook/form

Thanks in advance.