I need a cease and desist letter written - URGENT

I am involved in a network marketing company. I am running advertising on Facebook and have a competitor from a competing company contacting our leads, passing off as our brand, trying to sell their services to our prospects. I operate out of Australia running ads in New Zealand. The person contacting our leads lives in New Zealand. I would like a cease and desist letter written fairly urgently. Please advise quote and timeframe. Our brand (which I will give you on acceptance of quote) is currently have a trademark registered in Australia, not New Zealand. Thank you in advance.