I've just a call from Slingshot who are (that is? who is?) my ISP. They're upgrading me to their 50GB/$40 plan, I'm currently 15GB/$40, so all good on that front.
I'm happy enough with Slingshot, when things go wrong, which is rare, they are pretty hard to contact though, and do not respond to emails sent via their website.
The caller also offered to swap my home phone line from telecom to Slingshot, saving $7 per month. I can't see a reason not to, but thought I'd offer myself up to the vast internet knowledgebase, and ask whether there's any cons to swapping to Slingshot for the phone line.