Vodafone Invoiced for a Service I Never Received

During the pandemic, I applied for Vodafone home internet. They came to set it up, but since my last name had changed, they left without completing the process using my old ID. No paperwork was done, no modem, no internet—nothing at all. I guess they never initiated the subscription, yet now they're demanding payment for the internet service they never provided. Later, they even sent me a bill! And now they're threatening to start legal proceedings if I don't pay this unjust debt. It's outrageous that I'm expected to pay for a service I never received. How can they hold me accountable for an internet service I didn't even get? This is unacceptable. I do not want to pay it.