Lost my job, but MTN still expects me to pay.

I bought an iPhone 4s on contract in 2012. I missed one or two last payments and my contract was supposed to have discontinued. I couldn't pay the last payments because I lost my Job. I called Mtn to let them knw of this but they didn't assist me with anything instead they increased my montly instalment. I was supposed to owe R960, but instead I owe an exorbitant amount of R3500.I've begged and pleaded for this to stop but it didn't and now I also owe the bank for unpaid debit orders. The last thing a young person wants after losing a job is stress over something that MTN could have resolved by simply understanding the situation I was faced with and presenting a reasonable solution to my issue.