Help - signed modification form now bank says a different interest rate

[Mike]

I'm currently in-progress to modify the interest rate on my 1st mortgage. When I initially started the process and gave them my credit card they said I locked in the interest rate of 6.5%. Then I received my paper work to sign to start the process and that states it would be a modification to 6%. So I thought the rate had decreased and that would be the new rate. Now I talk to the loan officer again and he said the 6% rate was a mistake and it should be 6.5%. That seems like a pretty big mistake to me, is there anything I can do to get the 6% rate. I have not yet signed the form with a notary.Thanks.