recover site after hacking

[wwwanda]

I have a site/shop running in joomla 1.65 and now the latest virtuemart.
It was hacked a few month ago...
I did some manual cleaning up and updates and I thought everthing was ok again.
Then the credit card payment didn't work any more...
I got a developper who said cleaned everything, securized the site, installed an automated back-up, re-installed the bank API...
Everything looked fine !!!
But now,  the credit card paiement responds a message saying all cards we are trying to pay with are frauds !!!
E-mails  automatic replys when clients forgot their passwords doesn't work either !!
I am LOST !!! What can I do ?
I don't have a proper back-up before the hacking.....
Do I have to do the whole site over again ? there are a lot of products !!!
Thanx for any help and  solutions proposal.
I am willing to hire someone who can frankly solve my problem.

[jjk]

As far as I remember, Joomla 1.6.5 didn't have ACL (Access Control Level) implemented yet, but because the latest VirtueMart is tailored for Joomla 2.5, you would probably need to remove the ACL. So the solutions in this forum post MIGHT also be of interest to you:
http://forum.virtuemart.net/index.php?topic=118572.0

Also I would suggest to have a look at xampp, which is available here: http://www.apachefriends.org/en/xampp.html
It allows you to install a copy of your Joomla/VirtueMart website on your on PC and experiment with your site without the danger to destroy even more.
There are plenty of tutorials on Youtube and other places with "how to..." install xampp, Joomla, etc.