I don’t have much idea about HRM systems but you can check it out http://www.hotscripts.com and http://sourceforge.net/ . Might be you will get solutions.
I recommend open source project but also not deny that open source have some limitations so sometimes it is better that get some paid or customize solution means expert advice because there is no harm to put some extra money from pocket to get better solution.
It works in two ways:
1. It will reduce your pain and you will more concentrate on your main task and get more focus on your work so not only you can recover cost of paid solutions even get more profit in terms of productivity.
2. You don’t need to worry about small fixes which required in day to day working or may need in future.
At last every company want to use open source due to no extra cost but at last they have to get paid solutions when they required there necessity and budget so now all decision up to you means when you have to go with paid service providers.