Vodacom Fibre F up!

My Account went into arrears as they did not deduct there debit order and I never checked if they took the amount, I am a sales consultant and get deferent salaries every month. on my APP it always reflected as up to date so I was not worried, Yesterday they cat my service and told me I owe 12080. So went and checked my bank statements, true they never deducted but left my line on for 12 months before cutting it. If they notified me or cut my line after month 2 it would have been nothing to settle he amount and just carry on. Now When I call to make arrangements to pay the amount even though this is not my error they refuse and want the entire R 12 080 at once before reconnecting. I asked to pay R 2000 over 6 months and my instalment. They refused.