Discount Coupon Faking Payment Being Taken esp with Protx module

Following this thread here

http://www.zen-cart.com/forum/showthread.php?t=44876&highlight=discount+coupon

I will re-explain this problem.

Clean install on 1.37 - newsletter sidebox added, seo urls & image handler installed.

Payment method protx (initally cheque was also available)

Cutomer places order - enters discount code - protx is the default method customer complete the order and no payment is taken - site does not go to protx to complete the transaction.

This happens sporadically - but has happened to several different customers and the store owner has replicated twice - I cannot repliacte this error at all. (basically happened to about 10-15% of the customers on the site)

Discount coupons are set up as a % off, NO free shipping but with minimum order values. No zones chosen

This is a uk only site with vat (SWGUY FIX ADDED)

This is the steps the store owner took which repliacted the order ebing placed without payment being taken

Selected products
Entered discount code xxx/xx – then hit enter on my keyboard
It came up saying ‘continue to checkout’ – which I clicked
I intentionally didn’t tick the t/c box, and it then came up with the warning that I hadn’t ticked the t/c box.
I then selected the t/c button and hit the enter button on my keyboard
It then asked me to confirm the order – which I did.
Then I got the message saying thank you for my order

Payment is showing as being "protx" in the back office - when I previously had more than one method of payment available it was showing as GiftVoucher/Coupon

I.e defaulting to one payment method has not solved this problem (I thought initally ths customer was not selecting a payment method)

Having searched the forum I have found serval similar threads all with the same problem and with various payment methods being installed (paypal, world pay etc)

Please help!