In order to stop debt harassment phone calls, you’ve got to get tough, tougher than your opponents. If you can’t afford an overpriced lawyer — if you haven’t the beans to pay for his or her rent for the month — then you need to roll up your sleeves and do some in-depth research!
This means putting in some serious (serious, serious) time rummaging through the internet and, even (“even!”) your local public library. You better have what the Germans refer to as “Sitztfleisch” — or ass-meat, to put it more to the point! — since you’ll likely be spending a lot of time in a chair poring over this, that, and the other.