In the first instance, I’d write or e-mail your Property Manager (Agent) to formally explain that you have responded to the previous written representations by your neighbour and to those matters raised with them (i.e. your Agent) by the Landlord and the Owners Corporation, and that you vehemently deny making any noise of a type that would cause a disturbance. I’d include the fact that you work from home together with any other information to support your position.
Ask your Property Manager to forward that formal explanation / response to both your Landlord and to the Strata Manager for the information of the Owners Corporation.
Beyond that, I wouldn’t be too worried as if the Owners Corporation (O/C) is of the opinion that you have breached By-Law 1 (which relates to noise) then they are first required to issue you with a “Notice to Comply”; not letters of phone calls.
If the O/C is of then of the opinion that you have again breached (i.e. not complied) then that initiates a formal dispute resolution process involving the Strata Division of the Consumer, Trader, & Tenancy Tribunal where you would have ample opportunity to explain the situation.
By the way, a complete list of all By-Laws applicable to the Strata Plan where your Unit is located must be provided to you by your Property Manager within 7 days of your tenancy commencing; ensure that you have that for future reference.
You can read some further information HERE