MRS Associates Ripoff Untruthful change rules after agreement New Albany Ohio

I was contacted by M.R.S. Associates December 2005 regarding a collection account on a VISA bill. I explained that I would work with them to get the account paid off. We came to an agreement on repayment of the debt and agreed upon dates the payments would be made. The first 2 payments where paid as per the verbal agreement, the third payment I had contacted them and spoke to the regular associate I normally dealt with. I explained I was unable to meet the 3rd deadline and would there be any problems in pushing the 3rd payment back 10 days. The associate advised me there was no problem and to call if these new arrangements needed to be modified. I called M.R.S. Associates 5 days before the final payment was due to confirm the arrangements we had made and the funds for the final payment would be available as agreed upon. It was then I was told that the arrangements where no longer valid and that instead of a final payment of $1181.00 they now wanted $3876.00 in order to clear the debt. I spoke to the Director at M.R.S. he explained to me that because I did not make the 3rd payment at originally promised the agreement was null and void, even if his associate had approved the changes. They demanded the extra money to clear the debt. I refused to pay the additionl funds and sent an email stating that I was willing to pay the 3rd installment as promised. I have heard nothing back.
If my changes to the 3rd payment would nullify the agreement the associate should of advised me of this when I called about changing the final payment date. They dont care they just wanted there money. I am awaiting fallout from this.

Peter
West Jordan, Utah
U.S.A.