Making a tax return adjustment?

i just observed that my tax preparer made some heavy ....charitable deductions on tax returns for the last 2 years and I am now freaking out like crazy (about 5% of my total income each year...i make under 100k...but close to it) .....:(( ... I simply want to call the gov, tell them i made a mistake and return the money back asap....how do i do this easily while avoiding penalities etc ,,,since i am doing this on my own...and not after they caught me ? any suggestions ???? plz respond only if u don't enjoy being mean to strangers and would like to help genuinely !