Lower the rate and I would either lower the payment and allow prepayment, or get something from the customer in writing as to wanting to keep the payment the same. Because that is out of the norm, I'd want something in file.
It sounds like this is not the customer needing the protection, but certainly ready to collect on it.
My opinions are not necessarily my employers.
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell