I also could not get a response.
I noticed more negative feedback each day, and as I could not get in contact with them I made a eBay case. They have not even replied to that, and they have until the 20th this month.
I've also got my own tracking number, which is just stuck saying delivery booked on Friday 07 March, and the website "collectplus" says allow 5 working days before contacting them. I don't see that's my job to do, so I am just opting for a refund. Makes me think what is that tracking number for. I also ordered on the 28th February. That's just not good enough imo, I totally understand it was sent economy delivery but its way over the estimated date.
I would avoid this seller, but maybe others have had a better experience and I'm unlucky, but seems I'm not alone.