That's a good solution. I wasn't offered that.
Were you offered that option from phone support, Chat or in a store?
My "Phone not working with Mobile Broadband SIM" problem was solved by one of the guys in the Camberwell Store (who was excellent BTW) who set the APN to "connect" instead of "internet" or "yesinternet".
That solution is mentioned here:
Also detailed here:
I was having a private discussion with a couple of the Moderators, who told me about it, and enrolled me into it.
I think it's a new plan, probably being trialled, and possibly (I could be well off-beam here) aimed at what they call their 'legacy' customers - those who've kept their dial-up accounts going just to keep their email addresses active and who have no need to migrate to a broadband account. I believe it may be called the $5 Email Plan.