The usual terms say that you cannot have credit of more than £500 without the IP's permission. If you take into account the usual credit lines of utilities (gas, electric and water are often used first and paid for later) and car insurance on installments, this figure is usually blown out of the water already.
I would say that you need to heed your IPs requirements to get this breach remedied. Non-compliance will possibly see the arrangement failed.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk