Fix PHP Problem in Oscmax Oscommerce

I recently upgrade my oscmax from 2.0.25 to 2.5.2. Everything goes well except the new ultimate seo 5 once enabled made an unwanted removal of the dash between two values. I have a customized filter in product listing returns something like filter_id2=3-17 in url, but now it becomes fitler_id2=317. If I disabled seo, in cPath mode there is no such problem. I have filter short words set to 1 and remove all non-alphanumeric char set to false. The customized filter works fine when I manually change 317 to 3-17 in the url. I am not sure why the '-' is missing when seo is enabled. Interesting thing is in product info page the '-' is properly displayed as e.g. i-can-fix-this-problem.html. By the way no access will be given to the website, and I expect to pay no more than $10 and a quick fix. Thank you!