Can't logon on to my amazon.co.uk password reset doesn't work and customer support are useless.

I've had an account at amazon.co.uk for years. I've tried to logon recently and it says my password is incorrect, so I reset it using sms's and codes and the whole 9 yards. It changes successfully but the when I try and login with the new password I get exactly the same problem.

Customer support are hard to find and suggest that I set up an account under a different email. But I have a prime subscription so I don't want to do this. Terrible customer services.