classified expiration date wrong

the classified plugin expiration dates are showing up as incorrect

i have done several test posts today 12th december 2014

http://ilovestaffordshire.co.uk/classifieds/

and as you can see some adverts are due to expire in April and May 2015 however they were set for a 4 week expiration date....

also how can the expiration date be set by default at 4 weeks and remove the 1,2,3,4 week options....

thanks