Paid over $900 for COBRA after surgery, claim been “reprocessing” for > 4 months and getting debt collection calls

I had a question regarding what I should do about a health insurance cancellation.

I was, until a week ago, insured through Maryland health connection/kaiser permanente, and my insurance was canceled due to failing to make my monthly premiums. I’m supposed to make payments every month, on the 1st of the month, for roughly $160. The last payment I made was in July, and I confirmed over the phone that I was covered through August, meaning that payment included the August 1st payment. One of the advantages of going through Maryland health connection is getting a 90 day grace period, and provided that I have paid up everything I owe until the end of that grace period, I can make late payments without being terminated. As of October 3rd, my insurance was canceled, and I believe that falls within the 90 grace period.

I called Kaiser, and they advised me that they can reinstate my coverage if I pay them what I owe, which was always my intention, but I cannot pay them until near the end of this month.

Am I wrong in thinking that the health insurance should not have been cancelled yet? I understand that I am behind on payments, which is morally and financially irresponsible, and I fully intend to correct it, but am I still not operating within their terms by being within the 90 day grace period? If they did end it before the grace period was over, is there any other options for reinstatement?