You wanna cancel a credit card payment to a seedbank?
Really? You really want to involve your bank in this transaction?
Even if you had paid for a guarantee, that would still be an epic fail.
Personally, I'm no fan of the attitude, as they have now screwed me out of two limited drops and had to send me seeds I didn't want (and did not get to pick, even) instead.
But buying from any seed bank is a gamble on YOUR part, not theirs. If you really feel that their stealth was to blame, then just move on to another seed bank. There's like a dozen reputable ones. Some have better stealth, some have worse. However, if you're gonna be all butthurt if customs takes your seeds, then get the guarantee. It is there for a reason.