being victimised by the store

So I have an account with morkels and they managed to mess it up from the get go, I went to them 5 or 4 months ago time and time again trying to alert them to reduce my monthly instalment so my account won't be in arrears but they said they don't care that I lost my job and can't make the R1200 monthly instalment I asked them to reduce it to atleast 600 per month and they kept giving me the run around now everyday I have to put up with them calling me and harassing me demanding the money I don't have cause they didn't want to listen to me, I have to put up with them calling 5times a day and I still have to explain the same thing to them.<br> I need help with this cause now they are making threats about credit bureau whereas I had tried to explain that I can only pay them 600 per month