How can I fix my PulsaCoil A Class?

Hi, the water from the hot tap is running luke warm then cold but the boiler light is still green, although we don't think the 'over-ride' button is working. We've moved into a recently built flat. Which has been bought via a Housing Association. The defects period with them has literally just ended and they have said that they can't ask the Contractor to contact Glenhill on our behalf. So we contacted Glenhill directly but they have said they can't help until they're contacted by the Contractor!!!! Can anyone help please...