If i send them a written complaint do you think it is a good idea to include copies of the paperwork from my previous insurers to back up what I have said.

I have had my recent car insurance voided from inception by Direct Line and I am not happy with this as I have been given incorrect information by my previous insurers which has contributed to this happening. Here is a background to what has happened. I purchased car insurance from Octagon insurance on 12/11/2012 and at that time had 5 years NCB not protected. During this policy I had a fault accident on 31/10/2013 which I notified them of and had no further communication on the matter. I requested proof of my no claims some time after the policy had ended as my car was off the road at the time and I wanted to re insure the car. The document they sent me stated I had 6 years NCB not protected so it looked like no claim had been made as my NCB was not reduced. On the 4/6/14 I purchased insurance through the broker Sure Thing, the insurer was Highway. I had a fault accident on the 23/6/14 which I notified them of and had no further communication regarding this. I had my renewal come through from Sure Thing for the 4/6/15 and my NCB not protected had now increased to 7 years so I decided to renew. The following 12 months were incident free and I received my renewal for 4/6/16 and it stated I now had 8 years NCB, my renewal price from Sure Thing had increased so I decided to get some quotes online. After going on a few comparison sites and the Direct Line site I decided to purchase a policy from Direct Line starting on 4/6/16. On the application I put in the 8 years NCB and the at fault accidents/no claims made. As my NCB was not affected surely this means there could not of been any claims was what I thought. On the 12/08/2016 I received a letter from Direct Line asking me to contact them due to discrepancies in the information I have provided to what they have obtained. So I phoned the policy validation number and the man basically said there were claims for both incidents. He then accused me of knowing about this as I had done some quotes on comparison sites with a claim made which they had track of. I did do various quotes but this was purely out of curiosity to see what the price would have been if claims had of been made. I can see how this looks and they have now used this against me. On the 22/08/16 I had a text message from Direct Line saying that my car insurance with them is now declared void from inception. So Octagon and Sure thing have provided me with incorrect information and Direct Line have now voided my insurance as they think it was done deliberately. I still have the paperwork from Octagon and Sure Thing to show my NCB increasing from 6 years to 8 years with it not being reduced which is what would of usually happened if a claim was made and successful. As it stands I now have a void policy and I am unsure what the status of my NCB paperwork is now. If I had been given the correct information from my previous insurers then this would not have happened. This seems very unfair and unreasonable to me and I need some help and advice on where to go from here.