Remove A Family Member From My Policy

My daughter turned 19 in Nov 2013. She is on her 2nd car now with her own car insurance, We've been paying for her for over a year & we are not allowed to take her off my auto insurance policy by Pretak & Pagones in Poughkeeosie NY without proof. We put her on our policy over the phone & we cannot remove her over the phone. We did shopping & with her removed we can save $60.00 a mos. @ least. We like Progressive but she has had her own car & insurance for @ least a year. They will not budge on this. We've paid roughly $700.00 over the last year for nothing. Why? 2 other insurance co.'s gave us excellant quotes. The same quotes almost identical if my daughter was removed from our Progressive Auto Policy. $700.00 is a oil heat delivery for us. Thankyou.....