Part Time Worker/Casual Worker ?

Please help. My query is that last February 2010 I was put on a 3 day a week from then on I was paid 94.00 of JSB. I am on a low income and fall beneath the threshold to pay a PRSI Contribution. This month my husband rang to get the balancing statement for last year and they informed him that I had to pay tax on this JSB for last year. I really didnt know it was taxable. My query is now after reading all the posts that really I should have been on systematic short-time worker. As I was on a 3 day and should have been claiming for 2 days. What should I do. I know that this form of JSB is not taxable. Would this effect my entitlements or decision if my employer had more work available but then put me back on a 3 day a week that I would not re-qualify.

Thank you so much very worried.