Hi Lion61, I understand you're annoyance, there's nothing worse than feeling the site you're playing at is ripping you off. I think though I can explain the problems you're seeing. On a number of sites that offer free money to get people playing, there will often be a lot more playing with the free money than without (unless its a well established site).
Unfortunately a lot of people abuse these offers of free money time and time again and there's little to be done. Out of interest, how can you tell at Harry's if they are playing with free money or not? I think the reason you're seeing that sort of high percentage is because there are so many new free players compared to the regulars like yourself. Personally I wish sites would do away with the free money and concentrate on giving good match deposit.
Also, maxing out cards doesn't unfortunately guarantee a win. Harry's is EU licensed, and as such has to abide be certain regulations to ensure fairness and randomness. I think the fact you didn't win on your £70 is simply down to bad luck. Without knowing how many tickets everyone else had, it's impossible to say you should have won. I've had bad runs like that myself (about 3 years once in my own Bingo hall

)
As for the £50 withdrawal, that's pretty disgusting, but unfortunately all the sites on the Cozy Games have this ridiculous limit on them, and that's why I don't advertise them at this site at present. I have been planning for a long time to start a campaign for fair treatment to online Bingo players, and tackling stupid withdrawal limits like this is one thing I want to feature on the campaign.