Requesting Digital Voice Switchover

I'm aware VM are switching phone users over to digital voice. Is it possible to request this is done immediately, rather than waiting for VM to get around to our area?

The reason we want to switch is that we have terrible sound quality on our VM phone line, and the VM engineers who visited identified that it's down to a damaged copper phone cable. But the policy is not to replace copper phone cables any more, so we are stuck with bad sound until we switch.