Would I recommend Coral - No.
Would I use them again - Definitely Not.
In total, we have had two separate installations - a composite door and a bi-folding door and in both cases, we have had a number of repeat visits to address issues that followed because of poor installations.
The last visit from Coral was to fix a door lock that took nearly a month for fix from the initial call because they were ordering a part (this was not great because it is our primary door to our garden and considering it's summer, it proved hugely frustrating). My heart sank when he arrived and did not have the part because of a mistake in paperwork when the call was logged.
To add further misery, whilst the engineer was onsite, I asked him to review the composite door, that Coral had previously fitted. Since the installation of the door, we have had continuous issues with the rendering failing around the door frame and cracking. Despite a number of patched fixes, it had continued to be a source of pain for us.
The reason for the rendering issue, we found, was that the composite door frame had not been correctly fitted. The loose movement in the door frame that was connected to the rendering, was the cause for it to weaken and crack; hence any fixes that we applied were pointless.
The engineer was a credit to his company, and he rectified the issue for both bi-fold and composite door in a quick follow up visit, a few days later. The engineer even offered to address the rendering which was much appreciated. We did decline since we had already contracted someone to repaint and address the rendering around the whole house.
You judge a company on its performance and their ability to address issues. It is important to note that in both installations, there were mistakes that easily could/should have been avoided.
To Coral's credit, they will rectify any issues that follow, but from my personal experience, I will check any work more thoroughly and I will put my faith and trust in someone else next time.