Hyundai Edwin Swales ******

I have a issue with an aircon from this workshop. I have had my aircon repaired at this fitment centre and the work done was poor.I paid them in December and the unit still dont work. I have been running arounf and book my car and they ask me to come the next day. So now they tell me they have a new subcontractor and i must pay them separatly. Why as i paid them months ago. These guys are ******