Wow. They really did it.

[Chuck Linn]

I have been using auto pay for several years for my car insurance because it is cheaper then bill pay and I've had the same insurance for over 30 years and have had no problems. I will also be using auto pay for utilities because they send the bill out once a month and where I have been using bill pay now when we are on the road for 2 or 3 months have no way to get the bill to pay it on time so I will just let them take the money and I check my checking regularly so don't have a problem there. One place i don't use either auto pay or bill pay is my cable company but that is a problem with me and the cable company and that will be gone in Sept when we go on the road.

[H. Miller]

Back to the problem at hand...........
Aon is an insurance agent, not a company. Neither want to hear from an Insurance Commissioner (your domicile state).
In written form advise them that unless the matter is handled per your "many" notices to them (not renewed) you will be forced to contact your Commissioner and the Company in which they renewed your coverage.
Further, you want to hear from them (in writing) in __ days. I've always found that a "return receipt request/proof of receipt" gets their attention when using the US mail.
Harold