ADSL cut off and no NBN?

I have applied for NBN with Telstra on the 16th March. I was told by the man I spoke to that a tech would need to come to my home to do some work and that they would send me a modem. I was under the impression that I would continue to use ADSL with another company and cancel the service once I was connected. The modem arrived last week, and on Friday Telstra disconnected my ADSL without my permission! I now have no internet as well as no tech apointment date ( and apparently nothing at Telstra is working due to a failed upgrade ). Is this normal procedure for NBN connection? Have other people had their ADSL cut off before broadband is connected? I'm trying to juggle working from home as well as home edding three kids with no wifi and most of our devices are wifi only. My data will only stretch so far I'm really regretting switching to Telstra for NBN