the problem is that all the manufacturers follow the ISO standard for what is deemed "faulty". the ISO standard allows a certain number of dead pixels (and even more stuck ones) before it is classed as faulty, so even if you complained to the credit card they would just quote you the same ISO standard
most shops do have a returns policy though, similar to online, so if you noticed it the first time you took it out of the box, you should still be able to return it
credit cards are great when you actually have a case, but unfortunately the case for faulty pixels is stacked against the consumer, the only thing you can really do is check the product over fully before "accepting" it (e.g. the 14 day period for online or by making them take it out of the box and power it up in a shop)