Hello! My name is Miro.
I understand the problem, but you will need to know that some on-line services allow you to see account activity details, while others not. For example, both GMail and Yahoo! Mail track login activity and can display you an IP address and access type (browser, e-mail client or mobile phone) for every login. You can see account activity for your Yahoo! account by clicking THIS LINK
Read 2. What sort of information do we gather?
section, especially this part:Furthermore, certain non-personal information are also gathered, such as the version of the Member's and any other visitor's web browser (Netscape, Internet Explorer, etc.), the operating system (Windows 98, Mac Os, etc.) and the IP address of the computer from which they are visiting.
As you can see, they collect the IP address of the computer visiting Match.com so they must know who accessed your account and changed personal information. By "who" I am referring to the IP address of the computer used to access your account.
E-mail you received from Match.com is just an automated e-mail which is sent whenever certain changes are being made to Match.com account, so if you track that e-mail you will only see Match.com server information (IP address) and nothing that may reveal the identify of a person who hacked your account.
and you want to know that information since it wasn't you who changed personal information in your Match.com account.
I hope this helps!