Whats the problem with your 350 service - it might be an easy "fix" with help on here ?
Some have successfully gotten their SH2's reactivated but its a "slog" and you have to be persistent.
Your best chance would be to try calling “Retentions” on 150 or 0345 454 1111 (or 0800 9528046) - options 1-1-4-5 "Thinking of leaving" - they are open Monday – Friday, 8am - 8pm and on Saturday from 8am - 6pm. – [08.01 is best!]) you have a better chance of getting a UK call centre (it could still be a 30’+ wait though) who will be more understanding and helpful. Tell them you are thinking of leaving for Sky/BT unless you can get back to 200 and the SH2. You are probably in a weak negotiating position though as by getting the 350 you will have probably instigated a new 12 month contract and so could face "exit charges".
-------------------- 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.