Automatic customer group switch and discount?

[overseas]

Hello,

I would like to do two task automatically with virtuemart :

1/ Assign directly customer to one group depending of their reponse in customer form during inscription (To filter payment possibilities with country.)

2/Change automatically customer of group during a command by considering the number of commands and the amount to gives evolution of discount.
Example :
Bronze Customer 0% discount
Silver Customer 10% discount ==> number oc commandes > 2 or total amount > 100€
Gold Customer 20% discount ==> number of commandes > 4 or total amount > 200€

Do you know a way or a plugins to do that or do you have a sample of code to add in php file during commands and insciption of customers.

Thank you by advance

[overseas]

I have found  : Virtuemart Shopper Group Changer extension and it works well.