I had American Collectors for about 10 years, covering up to three cars at a time but had no claims. I just switched to another company for a couple of reasons, one of which was that almost every time I changed a vehicle something got screwed up. Like the wrong vehicle was dropped or the new one was not added. This was always when I did it online. When I then talked to somebody on the 800 line it got straightened out and very courteously too. My advice would be to not do things online but instead call them directly.
I had American Collectors (through USAA) for one year (no claims) and ran into a similar problem, that they screwed up the policy every time I tried to change something online. Then when I was deployed for a while, they decided to double the cost for one of my Model A's because I was not available to sign a form confirming that I had made the changes online via their secure website. Then I called them to ask about the increase (stacked insurance). The representative was really annoyed that I had called and she could not clearly explain the increase.

I ended up being on the phone with them for an hour and 18 minutes to try and fix what I thought should have been an easy quick fix.

When I got back, I dumped them (it was right on my renewal date). It seemed to me like they are technologically stuck in the 1980's.
When I decided to dump American Collectors, it was at around 8 pm in the evening. I called JC Taylor to ask about their rates and coverage and no one answered their phone

....so I called Hagerty. They answered the phone and were most helpful.

Got the new policy set up in about 15 minutes with all of my questions answered and explained in clear english. Everything (100% set up of the new policy) was done online as well. The representative with whom I spoke was a car guy too, so he understood exactly what I was asking about (driving, use of my cars, insurance coverage of spare parts, tools and related automobilia, etc). Hagerty's rates were slightly less as well with more coverage (and more miles on the towing/recovery package, etc).
Fordially,
Brad in Maryland