Why are you making me liable for my late husbands account

My husband passed away in December 2016. His car had to be sold. I have been bombarded by your consultants making all sorts of threats that I have to pay what he owes you. Merriam just called and Say's that she does not care that my husband is late , I must pay as your terms and conditions state. Why are you harassing me for my husband's account? The car is sold and has a new owner so I don't understand why must I be threatened like this. I have sent the contract he signed with Nissan and the death certificate and there is just no end to this fiasco. Please resolve this urgently and please be human, I'm sure that's not a hard ask

Mrs Twala