Tradus is a main store front, which took over Allegro and gave it the payu option, if you have already won an auction in Allegro then you will have to complete the transaction with them.
Are you using google chrome which translate the page in real time? that should help considerably.
It looks like the seller has restricted payment to options that don't deduct fees, i.e bank transfer. The only cost for the seller is the exchange rate, which you have no control, you just need to ensure you send enough to get the correct amount in their account.
One thing to note is that Allegro Buyer Protection Program works with bank transfers aswelll, unlike ebay which is only paypal. But there are restrictions.
http://uslugi.allegro.pl/pok/
Your only choice is to contact the seller to see if they can help.
Here is the safety centre, open it in google chrome which will translate for you.
http://allegro.pl/country_pages/1/0/sc/?page=1&sub=0
Personally, if you are unable to pay using payu or credit card and you are not too fuss about not getting the item. I would contact the seller and say to cancel the order. Better to be safe than sorry, not a big fan of paying through bank transfer myself. The choice is yours of course.
Alternatively, try to enlist the help of a polish member on the forum.
Sorry I can't be more help.