075-609-8660

Received several call from what appears to be an Indian call centre. Most of the calls were coming up as Overseas private but one did come through as 0756098660. All calls were claiming to save us heaps of money on our phone bill. Its not initiated from Telstra because they knew I was with Telstra so it must be a marketing campaign that is initiated from another telephone service provider which operates in Australia.
What you have to do is get Telstra or whoever you are with to identify the origin of the incoming call, you will need to provide a date and time and the information should be there in the call records. I doubt the 07 number is the actual number they are using, its probably like a storefront number. Once you know what the originating number is then you should be able to do a bit of research and find out who the company or organisation is that are making these nuisance calls. A little bit more research might even reveal who  in Australia they are working for.
If this seems too much trouble send an email or letter to the TIO (Telecommunications Industry Ombudsman) demanding that the number be tracked down to whoever is the initiator in Australia for these type of calls. If he gets enough emails he will certainly act.
If you have a suitable phone you can actually add the number to your blocked list and it will be filtered out and won't ring on your handset.

I am receiving up to 5 calls a day and have been for the last 3weeks since I told them off for calling me now they call then hang up how do we stops these call I added them to my do not call list but that has not worked

I too have had multiple calls from this  number - different people, and sometimes they hang up.  I don't know if they are selling phone plans, I don't give them the chance.

I have told them to stop calling this number, but still they continue.

I will ring Telstra tomorrow to stop this number - and get their advice on letting the TIO know about this.  Given the number of complaints I've seen, I'm sure they must already know about it.

These calls are relentless. No matter how many times you tell them not to call, they continue. 7 calls in the last 18 hours.
Why can't this be tracked and action taken?

phone spoofing explanation
http://en.wikipedia.org/wiki/Spoofing_attack
http://www.fcc.gov/guides/caller-id-and-spoofing
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Do consider maybe getting a call blocking device or phone.. You can google them and many are around $60.00 or so.

Report your callers here, not just to the DNC alone:

https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2

By State DNC lists:
https://800notes.com/faq/state-do-not-call

FCC Abandoned Calls Complaint form:
http://www.fcc.gov/cgb/consumerfacts/1088D-R.pdf
email:  fccinfo@fcc.gov

Call centre asking offering "cheaper calls on my land-line". Claimed to be calling from Melbourne, when quizzed about the 07 number, insisted she was in Melbourne, so I asked about the weather here today and she said she didn't know.