setcookie("name", hash, 0, "/");
print_r of the cookies before posting to https://paymentgateway shows that they are all there
however, on return from https://paymentgateway, an immediate print_r of cookies show that they are all cleared!
I tried setting time to time()+3600, as I thought it may be a case of a pseudo-browser-close, but that didn't make any difference.
If I bypass paymentgateway, my cookies are all there, so I've narrowed down the problem to the posting and redirection to the payment gateway.
I've run out of things to try