Don't be fooled pre-sale -- TERRIBLE after-sales service :(

Trying to open a new line with Home Connect and I was contacted within 24hrs each time - great service PRE-sale. Now that I've signed up and have some issues with it (after moving I discovered the infrastructure was with a different provider to what I'd thought), I'm getting ignored, and cannot get them to call me back. I've literally tried contacting about SIX times via various channels - emails, app, website chat. The former gets ignored, on that latter they promise someone will get back to me but they never do (that's the same channel I'd used to get in touch pre-sale, so it's clearly just filtering and not prioritising existing customers). I had the same experience before at my prev place - trying to get info about my cancellation there I was ignored until eventually used being on a sales call for the new line to get routed to someone who could help about the cancellation. Shame on me for not having learnt my lesson then I guess.