Finally got it sorted! Took over a month by I did it! After giving up again, I got another reply to 1 of the many tickets I submitted. This 1 though was much less generic. Basically I was told to delete the main game, JUST the game from my PS4. Leave the saves, then pop the disc back in, let it fully install before starting, load up the save and low and behold!! It worked straight away! So glad as I'd finished HoS and was halfway through blood and wine, 156 hours to date lol. Thanks to everyone who tried to help, really appreciate it