I am not sure what was the customization offer that previously is given to you. But I am sure you will understand that the customization of the theme is outside of our support scope and if my colleagues gave you a custom code it was to get you started on the customization which you need to continue the implementation in.
If you are interested in having custom headers without knowing the ins and outs of the code customization I suggest that you consider converting to Pro theme. here is a detailed information on the header builder which will give you a better idea of the product and if it is suitable for you or not:
Thank you for your understanding.