If you have been waiting more then 14 days for a postcard then I recommend getting in touch with GMB support to ask for help in getting verified:
1- log into your Google my business dashboard http://www.google.com/mybusiness
2- select support from left hand side hamburger menu
3- a help screen will appear to the right
4- Scroll down and select 'Phone' to request a call back from GMB Support. If not available, select 'Email'.
If the above steps don't work you can contact support via: