I have a signed contract with a window company that states i was getting Gorell Windows know they want me to change to Silverline Anderson windows. What can I do?

Cancel the contract. If the contract specifically states Gorell and does not include other language referring to allowable substitutes you should be able to cancel. When did you sign the contract? Was the contract signed in your home? You likely have a right of rescission as well. Silverline is not Gorell.