For info, I also have this problem. I tried twice, first time I received and email, with a link to active plesk support. in the support panel, no ticket open. got no ticket Id.
I just tried a second time, one week later. Didn't even receive a confirmation email, nothing...
Twice I went up to the 3rd step confirming ticket sending... I got :
Thank you for your request.
Your support request information has been sent to our support team.
Your unique problem Ticket Number has been sent to the e-mail address you entered.
For tracking purposes place this number in the subject line of your email when corresponding with the Support Team. All issues must have a Ticket Number to receive a reply.
Our Support Team will be reviewing your issue(s) as soon as possible and contact you via the e-mail address you entered in the online request form.
Best regards,
Parallels Support Team
But I received nothing, not in spam...