GNC Gold Card?

This confused me so i would appreciate the help.

I was in the GNC today purchasing the Prolab NLarge for £32. She offered me the gold card which i was under the impression was for free. I signed up for it and she gave me a temporary card. I paid £26 for the NLarge with the 20% discount from that card.

I looked at my reciept and the gold card cost me 9.99. Although im sure i only paid for the weight gainer, and not the gold card. 

When i signed up i gave them everything but my credit card details. Im confused, do i get a bill through the post for the gold card? 

No it gets payed for at the till.  Usually when you buy a tub of whey for £30-40 and get the gold card it works out the same price when you first sign up as you pay a tenner for the card then get the 20% off the whey etc.  Next time you go in it will be cheaper.

I haven't been there for ages though so it may of changed.

Gold cards are free at the moment, so I doubt you would have been charged.  Normally they are a tenner.  You will get the proper card through the post in about 6 weeks.