Master-Bag8111's journey

I was recently laid off from my position as Senior Manager of Marketing at a company where I worked for about 15 months. The company has a formal severance policy that states senior managers receive 6 weeks of severance pay. However, my employer is arguing that my title isn't relevant and is categorizing me as a 'manager' level, which would only entitle me to 3 weeks of severance. I've asked for documentation that outlines how this determination is made consistently across the company, but they keep avoiding the request or giving vague answers. It feels like they are trying to shortchange me with their reasoning. I'm considering whether I should spend $500 on a consultation with a lawyer to help negotiate a better severance package or if I should attempt to handle this myself. I've never been in this situation before and I'm unsure of my leverage. Any advice would be greatly appreciated!