Name changes can be requested here Profile Edit Requests but Request Policies & Procedures. Updated 6/6/2015 states that you need 1000 posts to be able to make a name change, or simply donate 25$ and get the perks of a premium member.
Perks of being a Premium Member
-Premium Member tag.
-No post restrictions on name & special title changes. (You can have an image/colored text title or name change regardless of post count.)
-No post count limitations between requests. (No need to wait 500 or 1000 posts to request for further changes or alterations.)
-Ability to change your own text title.
-Larger avatar dimension sizes
-Larger avatar file sizes
-Access to some elite sections.
-You will be a part of a special member's group for the life of the account it is granted to.
But still not sure if @Liz would change your name for nothing in return, because you simply want to change a letter from capital to small or vise-versa. Read the two threads that I provided above and try your luck. You can also read my HOW2MPGH guide for more basic info about MPGH.
Have a nice day.