Resolved this after (finally) managing to get some help via TOBI referring me to an online chat advisor.
1. Delete the Vodafone Broadband app from my phone.
2. Reset the router (pin into the reset hole); note that this is a factory reset so need to set new passwords up etc via the Vodafone Connect 192.168.1.1 webpage once this is completed.
3. Once the router is back up, reload the Vodafone Broadband app via the wifi connection.
4. Run through the app's setup process and it should find the router again.
5. Once the app's successfully linked then change the wifi network name, password; set up guest wifi network & password etc in the app or via the Vodafone Connect 192.168.1.1 webpage.
6. Will need to keep WPS ON in the Vodafone Connect 192.168.1.1 webpage as turning this off results in the Broadband app losing connection with the router!
A couple of comments on Vodafone's support (which appears to be designed to put customers off successfully getting any help):
A. Trying to phone an advisor results in being redirected to the webpage online chat capability - which is permanently loading (Firefox on PC, Safari on iPhone).
B. TOBI could only be accessed via the Vodafone account app, and that didn't work on the first couple of attempts.
C. Only got through to a live chat advisor once TOBI had been convinced it didn't have the answer.
D. Trying to post anything on here via Firefox results in everything being lost due to "content blocked for security reasons" even though I'm logged in! (Error 15, Access denied) - so that was the best part of an hour wasted. Managed to post this solution by emailing this to my phone and uploading it via Safari!
