We've had Amica for the past 30 years, and will be with them for the next 30 years. When we got our first policy with them, they were still a mutual company and we received annual dividend payments, which were generally about 20% of the policy premium. At the time, they only accepted your business as a new customer if you were referred by another policyholder. DW's family had been with them for at least 20 years prior to that.
I periodically do a quick check of what others would charge for our auto, and it's not even close. Amica is a full 30% lower than the lowest I can find. Home is about the same as with others. However, most importantly, we know Amica values our business as it was demonstrated when we had a complicated and very involved and lengthy claim on our homeowners policy maybe 10 or 15 years ago. When we inquired if we were covered, Amica immediately stepped in and took ownership of the entire situation, assigned a special group and case manager who handled all aspects of what needed to happen. To be honest, I don't even think we paid our deductible in the situation. Amica made what is generally known to be a difficult and expensive situation, into a completely pain free experience with a very successful outcome that cost us almost nothing, if anything.
Over the years, we've had minor auto incidents and our rates had never been affected by them. In each case, Amica acted quickly, and provided immediate support in getting things taken care of.
About 6 months ago, we added an umbrella policy, and they gave us a discount/refund on our home and auto policies with it.
Obviously we're extremely happy with Amica, and sorry that they've raised your rates so much in one shot for what appears to be no reason.
If after searching around for other rates you find that Amica is higher but not by a meaningful amount, consider sticking with them as it's also important how the insurer handles claims.