Insane amount of phone calls driving me up the walls

So we are having financial difficulty at the moment. Instead of paying my full instalments I only pay R65 short this gets me the very rude people working for this company to phone me 5times a day every day. At the end of the month I receive my statement and my money I paid on my account covers the phone calls SMS's and then there is about R20 left of my payment to go towards my account payment. Really people if someone at least is making an effort to pay their account and not just leave it for the wolves cant you just realize that we are trying the best we can. What about the people who just stop paying at least you're getting something from me. This is really unacceptable behaviour I really hope you don't land in my situation one day and you are treated this way. We are all struggling to survive and people like you will drive people insane.