Ripp-off's

I am not pleased with HomeChoice at all. I ordered two items: The call center agents phoned me to ask when I will be paying my first installment, of which I confirmed, they had a ridiculous amount of R387.65 that I had to pay plus the interest fee that was never explained to me, I tried explaining this to the agent but she explained her own version.

I called Homechoice and after waiting for 20 minutes, I spoke to a gentleman who understood me and I asked him to send me an e-mail which confirmed my agreed amount of R 183.36 over 16 months.

I paid that amount over for three months and in the last month I had to pay, their agents phoned me every hour, even in the evenings, to ask when I would be paying their R387.65 over. I tried explaining to them that it was incorrect but they started making threats of how I would be reported to their credit bureau so I didn't pay them and now I owe them R777.76 for missing a payment of one month which is three times more than I should've paid. How do I go about this without being in debt BECAUSE I will not pay for thousands whereby I am being **********.