Hi, sorry it took me so long but I couldn’t get hold of my friend (the one who works at mBank).
Finally met him though and this is what he said (all absolutely unofficial!):

When mBank and WBK started selling their prepaid cards, anyone could buy them. Obviously, because of the nature of the cards, lots of dishonest people showed up.
Problems started when those people decided to resell the cards.
Some of those guys were coping card’s numbers, selling the card to someone online and then clearing their accounts.
There were so many fraud complaints that the bank started blocking majority of cards purchased by individual people (not companies) who bought more than 10 cards. Just in case…
Eventually they changed their term of service and now you cannot buy the card if you don’t have an officially registered business. This way they can keep track of who is responsible for the security of the card. It seems to work, so WBK is just about to do the same.

My friend does not have access to the customer’s database, so he couldn’t tell me which companies are their resellers. But he said that as long as you can check that the company really exist, it will be fine.

I can’t really find anyone but Podex at the moment. But they seem like a registered company, they give the address, they made a professional ad clip and stuff: www.second-card.com. Should be reliable, right?

Thank you Coinfan for the advice. I've found this info though :
"Podex Card Silver cannot be shipped nor used in the following countries: Afghanistan, Argentina, Azerbaijan, Bolivia, Bosnia and Herzegovina, Burma, China, Colombia, Cuba, Iran, Kazakhstan, Kosovo, Libya, Moldova, North Korea, Pakistan, Panama, Peru, Serbia, Somalia, Sudan, Syria,Turkey, Turkmenistan, Ukraine, Uzbekistan, Vietnam"
http://www.second-card.com/?page_id=198

I need the card for my trip to South-East Asia, so Zachodni WBK is no good for me.

The thing is - since I'm from Poland, I've decided to go to the source and ask at the bank. They told me I cannot buy cards from them, they sell it to companies only. I asked about the problems with blocked money and they told me it never happened... They said they might have blocked a few cards but only if they suspected a fraud. Just a few cases, nothing on a big scale...

Anyways, I've just remembered I have a friend whose husband works at mBank (old schoolmate). He is out of town at the moment, but will be back in a few days. I'll call him and ask about details.

Hello, what is the conclusion then?
I wanted to buy one of those prepaid cards. I'm going on holidays next month and don't want to take my proper credit card with me.
But I'm confused after reading this forum...

Should I buy it from Mateo?
Or from Podex?

Any advice?
I'll appreciate help.