I need a legal letter

I signed up for a service 10 years ago for the rate of $17 and was told that this is the amount my service will be for as long as I pay on time. I just noticed that there was a charge for $19.98 on my account and called them to inquire. The customer service representative said that they tried to contact me by email last year to tell me that they were changing my service and monthly amount. I never received anything in writing from them and don’t subscribe to any paperless communication with them. I told them that I never agreed to this change nor did I ask to make this change. After the conversation, I was told that they would change my membership back to $17 and it would never increase. I asked for a statement of this verbal transaction to be documented and sent to me in writing at which time she said they did not have a way to do that. I believe I’m owed a refund for $2.98 for the last 12 months based on this situation. I want to inquire about having a letter written for this purpose.