Bug: Full payment of order with a gift certificate

[aftertaf]

Hi,
Using awocoupon for gift certificates : not sure if issue is with that or with virtuemart, so here goes:
We have gift certificates that people can redeem to purchase a product on our site. This means the order total is 0€

I created a fake payment method to handle this as per recommendations from awodev, but since the latest update (of awocoupon, or of VM 3.4.0, not sure...) it no longer works.
By this i mean that the shopper chooses the fake payment method and the following happens:

• if Ajax for OPC is enabled, we get the 'waiting for www.socouture.fr message for a good 30 seconds, then a modal popup saying Cannot update cart.
  If OPC Ajax is disabled, then the site returns a HTTP 500 error.
  

It works only if setup this way:
1. i make the 'fake' payment method NOT have the maximum invoice total to be >0.01, and in doing so making it appear before the coupon code is entered

2. i choose it as the payment method BEFORE i enter the coupon code.

Otherwise, the problem persists.

It also happens with OPC disabled, once i hit the 'select payment method' screen.


As a workaround I have set the fake payment method to no longer have the maximum order value set, which makes it visible (and a potential payment method for anyone to use, which sucks a bit but at least coupon codes work again...)

I've set minimum invoice total to be 0.001 on all other payment methods, but one stil shows (monetico, from alatak). i'll file a bug report on this separately...