ESA reassessment lost?

Hello. I contacted the service line to ask about the submission of my ESA form as I was concerned I would miss the deadline due to Sickness and a bereavement. I was told that it would be noted on my computer notes and that it shouldn't be a problem and he could make an appointment at the job centre for it to be scanned in and sent directly to ensure it arrived safely and make it easier for me. I agreed that would be very helpful and an appointment was made for the day after it was initially meant to be due in by as that was the earliest date they had available and the form would be received immediately by the assessment centre and I would have recovered from my gastric issues. My daughter was able to drive me and attend with me and a gentleman took my forms and said it would be scanned immediately and received within the hour. Ten days later I received a letter stating that I had not sent my completed forms and so a decision maker had decided I was fit for work. It said I could write and explain why I hadn't been able to submit it if I had a reason but I did write in the box where you tick if it's being sent late but clearly no one has read it, or the notes on my file or the whole things got lost? I'm so cross.
So now do I ask for an M R or just get in touch with them and ask what's happened?
I don't know what to do for the best.
Thank you for all you do!

Gordon, sadly no receipt was given or documentation returned but we did take a copy of all the pages that were written on.

Thank you we will. Another question, could the two
Day extension normally be used as a reason
for rejection even though the appointment to have it scanned at the job centre was
arranged by them when I rang? The DM clearly didn't look
at the computer notes they made stating this if so?