Upgrade from V11 to V13

We are running an ErpNext version 11 (v11.1.29 with Frappe framework v11.1.28 master) production instance running on CentOS 7.3 in our own cloud infrastructure.

We are missing out on several new features introduced including e-Invoicing which is mandatory as per government norms. We are looking for a partner who can help us to migrate the same to the latest version (v13) without losing existing data and customization.

N.B. Customization on the existing instance is very less only on delivery line items.

I am interested, please send details in private message