Missleading Promotions???

Just saw in a TV ad that betfair gives you 250 in bonus if you deposit 50 (Swedish crowns).
Thought it was a nice offer so I created a new account and deposited 50 kr.
Afterwards, no sign of the bonus, So I call the support. Now they say I probably have to deposit another 50 becoz the first deposit was under 50. WTF.... I JUST F----ing Deposited 50. Now becoz of their freaking transaktion cost, I have only 49.25 in my account.
Why the **** do I have to pay your freaking transactions costs? This was the first time ever I have been charged and scamed in this way. (and believe me it will be my last)
Now I want to withdraw my money, but it wont let me....
Why the **** didn't you mention in your ****ing ad that people have to deposit 51 kronor the get the bonus... Idiots!
I dont care about the money coz its only small potatoes. But it's just the principal of it...