O2 Techical error couldnt take my payment, now they cancelled my payment plan, threatning debt/coll

Axmatic

Hi, I hope someone can help if you are experienced with these issues. 
I ran into financial difficulty, arranged payment plan with O2, subsequently I needed more time so we agreed a new payment plan. 

They had disconnected my account but I was told once the outstanding balance was paid I could have the account reconnected. 

We arranged a repayment plan over 6 months, with the devices remaining disconnected until repaid in full. The sum was about £140 per month, and in six month account would be up to date. 

First repayment was due on 17th of this month, and then every month on the 17th. 

I called them on the 17th which was a saturday to make the payment as promised, but was told they had tried to take the balance in full via direct debit despite us having set up this payment arrangement. It's a qwerk of their system and I should have been warned if I didn't cancel the direct debit this could happen. When they try to take payment in full (in this case over 2k as they tried to take not just what was outstanding but all future payments on 3 devices also), the computer marks the account as nil balance, even if the direct debit will bounce. 

So they said they couldnt't take the payment on the 17th. The person I talked with talked with her supervisor. Who confirmed the following should happen: 

- I should call back on Tuesday to make the payment I was going to make on Saturday. 
- I should then ask to have the repayment set back up but over 5 months. This would keep everything on track. 

So on the Tuesday I get back through, and am told my device balances are now due in full and the payment plans have been cancelled. I asked the person to read his notes, and said the person I talked with said this would happen and the plan needs to be reset back up over 5 months. 

He said he can't do that and now the balance on devices (about £2000) is due in full, if not paid in 30 days they are sending it to debt collection. 

This week (tomorrow) i'm going to try to get in touch with a manger - and take things forward. 
But can anyone offer any advice? 

Thanks