I've had similar situations, and when I said, if I haven't received a bill or notice, how was I to know/remember it was due?
But the office the bill was sent from, told me, regardless if you didn't recieve one,if it had been lost in the mail,it was still our responsibility to call and send a payment. Though I was really pissed, I later realized they had a point, and sent a payment in.
Our mortgage company often screws up, sending our payment coupon/bill late, or even once while they were in transition. After the one time they attached a late charge fee to us once, I call them right away and say, "where is my payment stub"? Yes, I know I can cut you a check, but I can bet, without that slip your computer payment department will screw up, being lost of how to work outside of common procedure. I know for a fact, so I demand they send that month's stub and refuse to pay late charge if it is sent later than it is suppose to, they said if they are late like this to disregard it when they screw up.
Ah, I know it is so aggravating, especially when dealing with so many docs/hospital bills when there are things going on in the household with the family member(s) and their illness.
After dad died, mom wasn't taking and paying their bills, her dementia/care less attitude had herself putting the mail in grocery bags and shoving them in the closet, which I found, and then knew why nothing was paid and loads of collection agents were calling her, my husband and I, had to work so much with the agencies, to save her ***.
When we moved her, we did what my dad had done with certain monthly bills, put on direct payment, cause I know my mom is so gone, she wouldn't even write a check. But that is a whole other story.
I'm sending you positive energies,and wishes for luck with this stuff.
Take care now,
DE