Lincoln Financial Group Would not pay on a Dr approved disability.after knee surgery Internet

I work for a comapn in Souderton , PA they have had Lincoln Financial Group as our provider of Short term disability insurance. I went out for kne surgury ack in June of 2011. I was paid disability till August. At that point my company decided to change insurance carriers. Funny at that same point Lincoln decided that my Dr saying I could not work yet was not good enough and they stoped paying me . I have come back to work since then , but they still refuse to pay me for the two months that they kept denying me. I have provided document after document from the Dr and beged my company to help me . Nothing Nothing Nothing . THIS COMPANY IS A BAD COMPANY VERY UN ETHICAL AND ANY COMPANY THAT USES IS THEM IS UNETHICAL TO THERE PEOPLE