My business internet was not working at my supermarket and Called Optus and they told me that I could go to nearest Optus store and they will hook me up with internet solutions temporary
As I have many check out counters the Optus team told that temporary wifi dongle won't solve the problem and for that I would need Huawei wireless broadband box but they are not authorised so they connected me to Optus call centre and explained the scenario and they agreed to lend me the box and charges would be credited and than Optus store team generated a invoice which was put to my account and was told that it would be credited back
I did call Optus as my account was on direct debit and was charged amount of $296.84 and they told me that I would receive call back which nobody has called me back
I did noted the id of the customer support who made noted into the account that I won't be charged the time I purchased the temporary arrangement box form the store CP530740 (15295847648)
The reason of this long explanation is that I was told and was being assured that as its temporary arrangement for the internet and as your are our business customer we would be happy to make up the internet on till NBN service fault is not corrected
Please do look into it and update at earliest
Do let me know if you need more details on the case
You would be best to speak directly with business support to arrange a credit on that as the good folk on this public forum do not have access to any account information.
As @Yeldarb says you'll need to talk to Optus direct about billing.
FWIW the customer guarantees only apply to phone and not data supply. But it sounds like Optus have done the right thing and got you running again in the short term. Its not uncommon for credits to take a few months or have to be followed up a few times at Optus. You should get it back eventually though.