PIP appeal

Hi, I wrote a few weeks ago for help with my appeal letter. I have received the benefit and works letter stating what happened at my face to face meeting. If I need to add anything it says I have to phone. Am I able to write it down what I need to say and send it direct to the appeals office? There are many discrepancies in the report, I.e. I was able to spell world backwards . I was not asked to do this. I said I had a bank account, so I am able to understand money and paying bills. I did say I had a bank account but it is joint and my husband deals with the finances etc. The only question I was asked about money was to give change from a set amount. This I got wrong. Do I write these down in my letter? Thank you