After getting your service back on line last week, it looks like it was defaulted back to a 12/1 speed tier.
I think you should be on the 50/20 plan.
I have forwarded this on to our engineers and will hopefully be resolved ASAP within 48hrs.
I have escalated this to the NBN teams to resolve and hopefully done within 24hrs.' was not NBN Co who said my 'address is not connected to the NBN broadband network' and your records show July 2016 NBN FTTN Broadband XL connection. There appears confusion between both organisations! My speed has been improved this afternoon about half speed of the paid plan. Hope this continues to improve.
It appears there is another a conflict with another user trying to get connected at the same building/address, or something along those lines.
Someone will call you ASAP to sort it out.