Mortgage lender changed date on lock in--pls help!

Hi All, I have been having a lot of trouble with this lender--lies, lies, manipulation and more lies! Now we are well past our closing date. We started on a float rate. Over a month after "locking in" the lender finally sent us new a GFE, Truth in Lending and Rate Lock Confirmation all have different dates on them. The rate lock confirmation is the wrong date with a higher rate. When we told the lender about the wrong date she said there is nothing that can be done about it except that she will give us a credit after closing. Is there any way we can protect ourselves? and still close in a timely manner? Thanks in advance for the help. Mona