Unable to reinstate a debit order that they cancel

During February 2015 Woolworths cancelled for reasons unknown my debit order. After several phone calls and hours of being placed on hold they finally phoned me back and said that a double debit would be done on the account on the 20th of April. On the 21st of April they phoned me and told me that my account is still overdue. I again explained the situation to them. They promised to phone me back which didn't happen. I phoned them again thefollowing week and again explained the situation. I was again informed that a double debit would be done on the 30th of April. I phoned again on the 30th and explained the situation to them and that the debit order again did not run. I was told that they could see all the notes made on my account on all the previous occasions, but could not tell me what the problem is- only that they are monitoring the account. What am I supposed to do Woolworths? And why is it impossible to sort this out?