We received this from you today,
Mike, I rewrote this letter for you. I think what you were trying to say is this:
We are cancelling the Big Gas Thank You Offer because it has become unsustainable for us as a company. Unfortunately this means that you will see a 45 cent/day price increase in your gas bill.
If you have any questions, etc…
The problem with your letter is that you say you are amending something, when you are in fact cancelling something. I think that if you were running a bus company and “amended” a bus route you would find a lot of angry customers waiting at the bus stops along your cancelled route. Amend and cancel have different meanings.
Also, you say that will explain how this will effect my energy bill, but you don’t. I mean, not really. The sentence you were looking for is: “this means that you will see a 45 cent/day price increase in your gas bill”.
I am a teacher, and I tell my students that when they write a formal letter they should be as clear and direct as possible. I also tell them to back up their statements with facts and evidence where possible. This is something you might consider in the future. If you need any help in the future writing letters, please let me know.