ESA SUSPENDED

Can anyone advise me please? I am currently a full time student. I started full time education in 2013 when I was on Incapacity Benefit I informed the DWP that I was in full time education and in receipt of student funding and because my IB was contribution based this did not affect my entitlement to it. In November of last year after attending the medical and found to still have limited capacity for work I was migrated onto ESA and placed in the work group.
All was fine until last week when I noticed my ESA had not been paid on its due date. I rang them and they said my claim had been suspended because I am in full education and had not told them about it. As I had already informed the DWP when I was in IB I assumed that information would be passed onto them when I moved onto ESA. I also discussed this at great length at my ATOS medical in November and at the job centre in December where I attended a work focused interview.
I had no advance warning that my benefit was due to be suspended no letter or anything. As I am on contribution based ESA and in reciept of DLA I know that being a student does not affect my entitlement to the benefit so I do not understand the reason for the suspension.
When I rang them the person I spoke to did not know either, he left me hanging on the phone for a considerable amount of time while he went off to try to find more information but came back and said he could not find any guidelines about this therefore was unable to advise me. I've been told to send them proof of my enrollment at university but he could not tell me what will happen next. As I have passed their medical and the adviser at my Work Focused Interview was O.K about me attending university I am really puzzled about this and very concerned.
Thank you for taking the time to read this, any advice would be gratefully appreciated.

Thanks for the reply. When I was on IB I sent them my enrollment letter and proof of my student finance. They wrote back and said everything was fine and my payments would continue. I explained this to the person I spoke to about my suspension but she said that any information about me when I was on IB has now been 'archived' and they can't access it. I have now resend the information to the ESA department.