Administrators KPMG found a mountain of 50,000 invoices which had not been accounted for by the maintenance specialist.
The debt level was previously thought to be £46m to unsecured creditors, on top of the £22m owed to HMRC.
But KPMG told the Financial Times it was revising that figure following the discovery of thousands of supplier invoices which had not been processed or recognised in the creditors’ ledger.
David Costley-Wood, joint administrator and restructuring partner at KPMG said: “We were surprised at the level of backlog of invoices that had not been processed for a listed company.”
There is only £600,000 in cash available for unsecured creditors who are likely to receive less than a penny in the pound.
The creditors report, obtained by the Financial Times, said employee records held centrally “proved to be unreliable and in a poor state”.
“Relative to its size, it’s one of the worst payroll records I’ve seen in 20 years,” Mr Costley-Wood added. “The scale of the problem and the company’s debts was greater than had been expected.”
It is still unclear how much secured lenders – collectively owed £215m and which also include private placement noteholders – are likely to recover.