First things first - the SH1 should be a doorstop now. It only broadcasts 1 wifi band at a time (2.4 or 5 GHz) all modern wifi equipment does them simultaneously - including the SH2, SH2ac,Hub3,Hub4 - and VM are offering free upgrades for you (see below) which you may have tried?
I would say its worth doing because for the vast majority of customers the Hub3 is fine - we only see the ones on here for whom it isn't.
As the others have said getting your own equipment will always be better that that in the VM Hubs. But you wont know until you try - so get the upgrade and if it doesn't sort you then come back here for further advice. --------------
You could try the "free" SH1/2/2ac upgrade/replacement scheme - see the link below - as they are trying to get everyone onto Hub3's (may be a delivery charge).
It works first time for about 50% of customers, but if you get the - "Ooops - please call" message, then that usually means you are on an old package that the computer cant recognise so they want to speak to you about it. When you call it in it's a coin toss whether the agent knows about the scheme. If they do they will just say "ok we will send one out" (there may be a small delivery charge) - or - they say "oh no, that's an upgrade there will be a charge and it starts a new contract". Neither of those statements in correct - so just say no thanks and leave the call. Worth trying a second time as - different day = different agent
After that you could try texting on 07533 051809 - include account name/number and what the issue is and see what they say – replies may take a bit longer
Finally a VM person should pick this up here and sort the swap for you, but it can take several days up to a week.
-------------------- John --------------------
My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.