Banks' credit cards and their "marketing"

As an avid follower of kiasu-ism, I did what my "belief" told me to do: 宁可杀错也不可放过. And yet again, I was disappointed. I 杀错-ed. Sighs.

OCBC Robinsons credit card was having a roadshow in John Little the day I was shopping with girlfriends. The standee banner was marketing the credit card saying that by signing up the Robinsons credit card, upon approval, the applicant is able to receive $80 worth of vouchers that can be used in either Robinsons, John Little and Marks & Spencers. (Too bad I did not take a snapshot of the little booth)

So, being the kiasu me, I signed up for it. Girlfriend asked the promoter if there is any terms and conditions like spending a minimum before using the vouchers. Promoter said No. And guess what? Girlfriend and I both had our applications approved, and both of us were greatly surprised. There are three vouchers, in denomination of $50, $20 and $12. To spend the :

• $50 voucher, which is only valid for Robinsons stores and is "Valid only with a minimum nett purchase of S$250 charged to your OCBC Robinsons Visa Elite or Platinum Card". 
• $20 voucher, which is only valid for M&S stores and is "Valid only with a minimum nett purchase of S$100 charged to your OCBC Robinsons Visa Elite or Platinum Card". 
• $12 voucher, which is only valid for John Little stores and is "Valid only with a minimum nett purchase of S$90 charged to your OCBC Robinsons Visa Elite or Platinum Card". 

And of course other terms and conditions which the lady promoter failed to address. Of course, it was my own mistake to be greedy, obviously there are no free lunch in the world. Just letting off a little steam since the promoter did not do her homework, and was assuring us that we can just spend the vouchers at any of the 3 stores without minimum purchases. Now the vouchers are simply useless to me. I don't really usually spend THAT much in one go in these stores and I can't shop discounted items either. 

Now, I do not know what to do with the OCBC Robinsons credit card that I greedily signed up for, and the OCBC Pink by-procedure-I-have-nochoice-but-to-signup-in-order-to-signup-for-the-Robinsons-creditcard Titanium credit card and the EasiCredit with cheque book, also a by-procedure-I-have-nochoice-but-to-signup-in-order-to-signup-for-the-Robinsons-creditcard. 

Girlfriend felt like cancelling all these especially after feeling so "cheated". Should I do that too?