need little help in canceling a registration letter of a class?

i registered for a class 3 days ago and then i find out i wouldnt be able to take that class because i m not gna be here at that time so they told me to write a cancellation letter, i paid the fee and they said that they gna refund that, but my question is that in that cancellation letter do i need to write that can i get the refund back please or that’s little wierd i wrote that i want to cancel the registartaion i make but i was confused if i should write about refund is this appropriate ….please help