We're terribly sorry to hear that this has happened and want to give my deepest condolences to you and your family. It is likely that our system has automatically generated the letter and appreciate that it does sound insensitive. I'll get this fed back to the Team to see what changes can be made.
I can look into this for you if you would like? Make sure nothing else is sent and the account is closed? We do have to send all letters to the account holder, I am so sorry and can understand this can be distressing.