Hi,
Let me come straight to the point.
I have recently worked on a spreadsheet implementation of a forecasting model.I have tried both ARIMA and holt winters forecasting and got better accuracy with both. I am proficient with respect to Excel and VBA as well.
After going through your attachment, I am confident enough and can finish your work in just half a day. Let me know if you want to discuss further.
Regards,
Sahil