The company said it is also co-operating with a nationwide GLAA investigation into how companies recruited 20 Indonesian workers.
Last summer, those workers claimed they were charged illegal fees to come to the UK by recruitment agencies abroad.
The Haygrove spokeswoman said: "We are deeply concerned by claims that Indonesian workers were charged illegal fees by recruitment agents, which is strictly against our policy and principles."
She added that the company took any allegations of misconduct "very seriously" and had "co-operated fully with investigations by the GLAA".
Haygrove is "committed to fair employment practices and the wellbeing of all our workers", she said.