Operating a business from a residential unit

Would like to tap into the wise and experienced who use this website.

1.  Use of a residential unit:  One of our units has recently had owners move out & tenants move in.  The owners told us it was some students moving in however this seems inaccurate. These tenants don’t seem to live here and appear to be using the unit solely to run a business. We are in a suburb of sydney about 20 mins from the city.  A tradesman who the OC had to call out to the unit to fix something told us it contains  many desks and a bank of about 10 computers.  We see a number of people come each morning and leave each afternoon. 

One of the tenants indicated to another resident that they were running some sort of stockbroking business. 

 Can the unit be used for this commercial purpose without the Owners Corp consent in advance?

2. Requirement to install extra phone lines:

The owners or rental agent also told the tenants that there would be two or three separate phone lines available.  To our knowledge all the units only have one phone line coming into each unit.  The tenants are now saying the extra phone lines are not working & they are demanding this be fixed urgently. Our strata manager says unless we can prove that there was only  one line when the property was built  the OC will be responsible for “fixing” this.  Telstra will not do it so our strata manager called out a specialist installer who tells us “this will cost many many thousands of dollars”

Seems unreasonable approach. Surely the onus is on the unit owners to prove there was more than one phone line rather than the OC having to prove there wasn’t more than one.

Any thoughts gratefully received !!

Thank you