Window Scratcc - What's best to get it out?

Hello, never posted before so bear with me!  We have a 20yr old motorhome and one of the windows has a deep scratch about a metre long courtesy of the previous owner getting too close to some barbed wire.  Is there anyway it could be polished out and, if so, with what or are we resigned to replacing the window?  Any advice would be most welcome.  Thank you