I've had similar experiences myself in the past. One thing you could try is firstly bite your tongue and be very polite (to the parasite whom you are talking to) and make out that your a bit hard of hearing.
Ask the parasite whom the company is that it represents and then write down their particulars - all the time making out that you're struggling to hear them. This way (hopefully) you'll gather as much information as you can without alerting them to your ploy.
With a bit of luck you can then use this information to report them.
The only other thing that you could is is to get anonymous caller rejection installed - this way the callers won't be allowed to contact you unless they allow their number to be recorded.
Good luck and I hope you have some success.
Si thee
