"Wondering what else may be wrong"

I received a letter today addressed to myself from the hospital asking me to attend an appointment within the respiratory unit. I was a little confused so rang for clarification to be told it was a follow up from my last appointment. I explained that that had been five years ago and they said they would look into this. I was informed that the mistake was down to the wrong CHI number which I find worrying and makes me wonder what else might be wrong on my medical records/notes. I would like someone to look into this and to reassure me. I am currently isolating from a second infection of Covid and feeling unwell and this has just added to my worries at this time.