Compensation assessment wrong. Can I claim again?

[Guest]

Hi, can't seem to find anything that tells me whether i can pursue this or not. I was assessed and told my condition would be better within 6-9 months. It was 'only' whiplash so i thought this was right and settled my claim. However it has been 18 months now and i am still struggling with work and home life due to the symptoms. I have heard you cant claim twice is that true? Thanks