Dear …
RE: Account __(Name and #)__
I am writing to you today as a request to __(name of organization)__ to offer me a lower interest rate on my __(type account)__.
I have been dealing with __(name of organization)__ for __(#)__ years now, which lends itself to being considered a loyal customer. In addition to that, I have proven myself to be an excellent credit risk over the years. As a very conscientious citizen, I have worked very hard to build a good credit reputation ensuring that my payments are always made on time and staying current with all of my credit obligations.
For all these reasons, I believe that a lower rate for my account would be justified. I am hopeful that you will seriously consider this request and I look forward to hearing from you soon.
Sincerely,