Hi Pier!
Thank you for interested in our product.
The invoice number can be customized but can you help me to clarify how do you want to customize this?

Hi Pier!
Can you give me your order number or email that you use to purchase our product?
About the invoice number, if you want to do like your example, you need to pay a small fee is 50$ for customization so that we will do it for you correctly.
If you have any questions, don't hesitate to contact me via Skype for fast discussing: Vincent_4281.
Regards,
Vincent

Hi.
For me it is not correct that I can not change by myself the format of invoice number. Why this? At this moment I don't think that I will pay 50$ for the customization.
I thought that this product was very good, but now I will not recommend it.
Thanks,
Pier

Hi Pier!
You need to pay a customization fee because our product has the fixed format for the invoice number.
Btw can you give me your order number
Vincent

Hi Vincent, thanks for your answer.
Yesterday I bought the product and I need to customize the format of invoice number. At the moment it is 11-0001, 11-0002 etcetera. I need to change the format into 2017-0001, 2017-0002 etcetera. And I need to start from a specific number: 2017-0002, then next year the format of the number will be 2018-0001, 2018-0002, 2018-0003 etcetera.

thanks for your help.
Pier