Their mistake, but please pay

I received a phone call from Woolworths loans department in January saying that during December no debit orders went through because the system crashed and that I am in arears now. I had to pay my loan amount for December and all will be fine. I payed immediately because I've never in my life been in arears. February I received another call from the department saying that I have to pay double my monthly fee because I'm in arears. When I asked them how it is possible, they said that if the system is down all debit order customers are kicked off the system and until you pay every last sent you are in arears you have a negative mark next to your name and can't be put on debit order. No-one informed me of this in December or January. Now they say they are so sorry but they can't even make an arrangement for me so that I can pay a little extra each month. I have to go into the store and ask until I'm all paid up and there will be interest. I'm a teacher I don't have thousands of rands to pay one shot and that because they made a mistake and never told me. Funny enough my sister's debit orders are still going through and she's not off the system. What does that tell you.