ER has replaced Michael Heap with the former UK boss of American music group Warner, Nick Phillips.
Phillips will be tasked with delivering value to shareholders and re-establishing their confidence.
The firm has also confirmed it’s in preliminary talks with two potential buyers, but it said investor were unlikely to accept offers.
"The company reiterates there can be no certainty that any offer for the company, if made, will be at a level which would receive sufficient support from shareholders," it said in a statement.
The firm’s shares have fallen 73 per cent over the last 12 months.