My first question is, are you sure you didn't go through Paypal? (Auctiva checkout can look very different)
Just to double check, log into your PP account and see if this transaction shows up. Usually the Auctiva link takes you to Paypal. If not, the seller most likely has a merchant account where you would pay directly with a credit card. If that's the case, wait until 45 days have passed and if you still haven't gotten your item you should be able to do a chargeback with your credit card company.
Just FYI...Auctiva is a listing service so they would not be able to help with anything pertaining to not recieving your goods, or payments, etc. But it's good to see that you are exploring all avenues to find assistance
Please post back to tell us how it turned out.