Google APPs managed "unlimited" account storage quota for service account

I have a Google account as a student. This account is managed by my university and recently the university informed us that students' accounts have now "unlimited" storage for Drive etc.

To perform backups with this, I created a few service accounts in Google APIs console ([email protected]). But it turns out that those accounts' storage is limited to 15GB, that is, when trying to upload files to one of service accounts that already has ~15GB in it, I get an error "the client is exceeded his storage quota".

I asked the university admins, they don't know how to help and even don't see the service account' email ([email protected]) in the list of managed accounts.

So the question is what should be done (by me or by university admins) to remove (or increase) the storage quota of my service accounts when those were open with the "unlimited" student account.

Update: trying @DaImTo suggestion:

So I created a folder in my Drive web interface and shared it with my service account. Then, with service account, I uploaded a file to that folder (using PyDrive library):

file1 = drive.CreateFile({'title': 'test2', 'parents': [{"kind": "drive#fileLink", "id": shared_folder_id}]})
file1.SetContentString('some text')
file1.Upload()
print 'File ID: %s' % file1['id']
permissions = file1.auth.service.permissions().list(fileId=file1['id']).execute()
print "permissions:", permissions

Output:

File ID: XXX
permissions: {u'items': [{u'kind': u'drive#permission', u'name': u'[email protected]', u'domain': u'developer.gserviceaccount.com', u'etag': u'"XXX"', u'emailAddress': u'[email protected]', u'role': u'owner', u'type': u'user', u'id': u'XXX', u'selfLink': u'https://www.googleapis.com/drive/v2/files/XXX/permissions/XXX'},
{u'kind': u'drive#permission', u'name': u'<my name>', u'domain': u'<my school domain>', u'etag': u'"XXX"', u'emailAddress': u'<my name>@<my school domain>', u'role': u'writer', u'type': u'user', u'id': u'XXX', u'selfLink': u'https://www.googleapis.com/drive/v2/files/XXX/permissions/XXX'}], u'kind': u'drive#permissionList', u'etag': u'"XXX"', u'selfLink': u'https://www.googleapis.com/drive/v2/files/XXX/permissions?alt=json'}

So the uploaded file automatically has two permissions: 1. Service account is "owner" 2. My main account is "writer"

Indeed, I can see the file in web interface, edit it , delete etc. But, since the service account is the owner, the file is accounted in service account storage quota, so this doesn't solve my problem, i.e. I still cannot use more than 15GB with my backup application.

I tried to transfer the ownership to my main account:

file1 = drive.CreateFile({'id': file_id})
permissions = file1.auth.service.permissions().list(fileId=file1['id']).execute()
myperm_id = permissions['items'][1]['id'] # this is the second permission, i.e. of my main account
myperm = file1.auth.service.permissions().get(fileId=file1['id'], permissionId=myperm_id).execute()
myperm['role'] = 'owner'
file1.auth.service.permissions().update(fileId=file1['id'], permissionId=myperm['id'], body=myperm).execute()

...and got an error:

googleapiclient.errors.HttpError: <HttpError 403 when requesting https://www.googleapis.com/drive/v2/files/XXX/permissions/XXX?alt=json returned "Insufficient permissions for this file">

I tried to append transferOwnership='True':

file1.auth.service.permissions().update(fileId=file1['id'], permissionId=myperm['id'], body=myperm, transferOwnership='True').execute()

got the same error. I'm stuck here.

Btw, in Google help Transfer file ownership they say "If you're a Google Apps user, you can't transfer ownership to someone else who is outside of your domain."