I made 2 claims last year for a rope and then a French fishing net around the prop.
Despite filing them online as requested they denied receiving them. Their office was also very difficult to contact by phone and I think they were seriously understaffed at the time.
Once I submitted the claim by post (recorded delivery) the claim was settled in full within a week. They were also quite happy that I had the boat lifted out of the water again when we returned home so that my engineer could double check the repair that had been carried out in Guernsey.
I have been insured by N&G for over a year now and thankfully not had to make a claim. However, I am very impressed by how easy it is to get hold of them. I have made a number of changes to the policy so have called them on maybe 10-12 separate occasions - and apart from a couple of times early last year where I got a recorded message, I have since got through to a real human first time in a few rings. No call centre or asian outpost - but a real old fashioned office like it used to be last decade.
I get the impression that if you had a claim, there would be someone at the end of a phone to shout at - unlike most other organisations. BTW, I did try and renew the insurance this year by internet which failed. Maybe their internet system is screwed up - but a phone call the following day sorted it.
I've been insured with them for about 6 years. Made a 3rd party claim, through a broker, a couple of years back which was handled totally to my satisfaction.