i paid online for what i believed was the official site for the dvla theory test but they charged me 20 over should have been 32 and was 52 dont no how to reclain it

i recently searched through google to book my theory tast online, the first item that appeared was theorytest.net. i clicked on, booked my test and was told i would receive a confirmation email within 2 days. i never received this email however the money was taken from my bank account:
Here is a section of my bank account statement as proof of payment:

29/01/2010
Card Purchase
-£42.00

PAYPAL *ISCOPEMILD
REF 027 0838771100 BCC

I returned to the site to enquire when my test was booked for but there is no contact details for them. i eventually found an email address through the websites terms and conditions, [email protected], i emailed my enquiry to be told i did not book through them as i paid £42 they charge £51. I am absolutely positive i booked it through them as i always save important sites to my favourites.

I have been conned what should i do?

(my email- [email protected])