I used Chronomics today and no issue. They have a 5 day lead time so I ordered and said my departure was earlier than it actually was so I would receive it earlier.
They sent a dispatch email saying it had been sent by DPD and to use my order number as the tracking number and it worked fine, delivered 2 days after it was dispatched.
I registered the kit, did the test, sent the photo and within a minute the certificate was issued. I uploaded a copy to Verifly, all fine, and I flew home today.
I've ordered another kit today to keep as a spare incase getting a test locally overseas is problematic. Does the job for £22.40 in my opinion.