Lemon Juice and Vinegar Stain Remover Discolored Couch Cushion

I got a dot of permanent marker on my new brown microfiber sofa and I read on a website that lemon juice and vinegar worked so I used those. I think I might have discoloured the fabric. How can I correct this? I am not sure if I have or not? How much would it cost to get just a new seat cushion replaced? Please help.

By Tonya from Canada