2.3 Url format back to 1.9 format

Hi,
I have recently upgraded a inherited 1.9 nopCommerce system to 2.3 but am now getting a bunch of emails from the SEO company responsible for the site who are basically telling me to change url format back to how they were in 1.9 due to back-links they have created. SEO isn't my area so I'm not sure how much work it would be at there end to just change the links to be the new links.

Regardless, I have tried changing the catalog mapping first in the RouteProvider.cs to mimic http://www.thestore.com/category/13-test-product.aspx

routes.MapLocalizedRoute("Category",
                            "category/{categoryId}-{SeName}.aspx",
                            new { controller = "Catalog", action = "Category", SeName = UrlParameter.Optional },
                            new { categoryId = @"\d+" },
                            new[] { "Nop.Web.Controllers" });

Although the link is rendered correctly, I receive a 404 error when I attempt to navigate to a category page.

Greatly appreciate anyone shedding some light on this.

Cheers!