The problem is probably linked to the fact that that VM have run out of Hub 4's required for your broadband speed boost to 1 Gbps. Or rather "stocks are low", and as is normal with VM, new customers get priority over existing customers. Because VM operate under a "sunny side up" policy, they never admit to problems, so staff can't say any of this.
What can you do about this? Not much other ask about cancelling and the retentions staff you speak to might then find you a Hub 4 (no guarantees on that). Complaints often get fobbed off, so I'm not hopeful that will help you. When VM manage to sort out stocks of Hub 4's then they might get round to issuing to upgrade customers who are in the same situation as you, how long that will be I've no idea - a couple of months seems a fair guess.
I hazard a guess the problem exists for you because of the combination of:
1) Global semiconductor shortage and logistics disruption (new supply of hubs is constrained)
2) An unexpectedly high take up of Gig 1 and Volt upgrades (more hubs needed than are available)
3) You're an existing customer (a second class customer in VM's eyes, so back of the queue for you)
