Hello my question is i had a judgement against me and have been paying monthly,but not covering the 12% which was unknown to me.

12% interest is pretty steep, but unfortunately, that is what Massachusetts law provides for in what is called "post-judgement interest" (there is also "pre-judgement interest").  The purpose of the law is to encourage settlement by scaring people with a ridiculously high interest rate.  The more unscrupulous collection companies use this to generate profits, while the people who are really interested in just collecting judgements for money owed to them will often waive pre and post judgement interest as part of a settlement.