Hi
I administer these systems in a university. Normally if a student does not have a valid IT or Turnitin account (and where I work the Turnitin account is administered via the VLE - Moodle in my case) then the core issue is with your identity at the university.
When a student comes to me with these queries the first question I have is:
"Are you completely enrolled?"
Followed normally by "Have you paid or made arrangements for the paying of your fees?" and "Do you have a valid IT account"
We consistently turn off IT accounts and VLE access for students who have failed to enrol completely, failed to pay fines or failed to pay fees. It proves far more effective in motivating students to do things they should have done than constant emails which they can ignore.
As a student it is your responsibility to ensure you have completed all the process correctly and fully and I would strongly suggest you contact your Registry to check your status. After that, contact the IT helpdesk to check you have a valid IT account. Depending on where your VLE is administered, some universities house it in the IT department, others site it in teaching teams, you should also contact the Turnitin administrator, who is probably also the VLE administrator, to check your data is correctly loaded. You will be able to find out who this is from the university website.
The point I would underline though, is that if the University is telling you they can do nothing, then the issue is almost certainly at your end i.e. something you have not done or not completed or an instruction you have failed to follow. Believe me, universities are not in the business of randomly failing students because of minor IT niggles.