Good day,
I would like the opportunity to develop this calculator for you. I have been working in a banking environment for the last 5 years. I develop in C# and have my own server where I can host this calculator for your and include in your site via direct link or iframe etc. I will host this calculator for you, but will also provide you with the source code if you do feel you would like to host it elsewhere. I would however require the calculation requirements in a specifications document from you though. I take a lot of pride in my work and would like to make this calculator and its functionality become available to you again.