misleading "coupon" offer

ordered vitamins online. At the end, when the invoice page came up, a pop-up window appeared, offering $10 "coupon" towards next order. There was a button to click, & then a space to enter email address. After I submitted my email address, I found I had just ordered a subscription to a discount shopping club, which will debit my account for it's monthly fee of $15, using the account information I submitted when ordering vitamins from VitaCost.com. Now I have to call & cancel the subscription with DealMax or SavingsAce, or whatever it is. I called customer service at VitaCost, to attempt to stop my order & my account information from being sent to these partner merchandisers, and was told it was too late. I went through something like this once before, & it was a scam. It took me 3 years to get my money back after a class action lawsuit. I am enraged. Needless to say--no more ordering from VitaCost!