This is just my opinion - if developers like to add this option [support tickets].
To make a link - its easy, but user then have to enter again their user id and pasword for that too.
Many a2b lovers using this program to sell PIN online or to recharge their account. As my opinion, Uers might have problems, so they can create tickets under their account rather than sending emails to you - and it will be easier to track their problems.
If this a2b is just used as for calling card that users buy cards from market and use the PIN then this support tickets is absolutely valueless.
There are quite many program about it. but
We are using "Help Center Live" - what you can get under fantastico of cpanel. I will install another one and give you access for both user & admin. but this "Help Center Live" is having many features.
it is better to have very simple feature as like
http://www.voxbone.com [one interface to create ticket under user account and other interface to check & answer those tickets under admin account ].
Thank you all.