When moving house I requested to move my nbn service to my new address. After successfully completing this order request i was contacted to be notified of plan changes that i should accept prior to the move. I accepted them. On the day of the move i checked that the service was operational and it wasn't. After 20 days of back and forth communication and 1 to 2 hours per chat, they still hadn't connected my service with the excuse that some config needed to be done, so I cancelled it. 4 days later I am still not disconnected and keep getting platitudes. My new service provider called me to say they cannot proceed with connection until optus have deactivated their service. I am at my wits end. So in all I have had no connection for 22 days, I cant even cancel successfully. I have had countless promises of 24 to 48 hours and escalation promises. No one from optus calls me, i have to do all the chasing. I will never use this company again. Level of care-0, level of support-0, level of service-0. Ridiculous!!! I AM STILL NOT CONNECTED OR DISCONNECTED .....
Any provider who says "We cant connect you for NBN until Optus disconnects" is feeding you absolute rubbish too. Choosing another provider would get them to log an order, unless the Optus order is still 'in progress' and awaiting a tech/NBNCo to do something.
Your best bet is via www.optus.com.au/complaints and get the Customer Relations Group involved.
I'd suggest the other provider is probably correct. After all why would they say you can't get the NBN with them if they could? Logically most technologies the NBN uses can't provide two connections to the home simultaneously (except FTTP). so if OPtus has an order in place then presumably NBN won't superced that until Optus agree.
I had a workmate who had the same problem recently. Simply wanted to join the NBN with a new Telco. However it turned out he had a long defunct fax number associated with his Telstra line and the NBN wouldn't move forward until it was released. Telstra kept saying it was released for about a month before it finally got sorted.
But the other ISP is really peripheral to all this. Where is Optus? Why do Optus customers have to chase down resolutions and not be contacted with updates and options proactively? When it comes to the NBN in particular the role Optus plays is very specific. They are the intermediaries between NBN and the customer. The customer can't contact NBN directly to resolve issues. Only Optus can do that.