Steve from Paragas arrived within 2 hours of my call and promptly assessed the problem. He explained, very clearly, what process of diagnosis he was following and kept me updated as he eliminated the initial, possible causes of the problem. Once the need for a new expansion vessel was confirmed, Steve, got the boiler running again and explained how to keep it going temporarily until the replacement could be fitted. He also suggested that I check with manufacturers to see if it was still under warranty and if not to ask what their best repair package would cost, so that I could compare it with a price that he would quote me later on the same day. All work carried out in a clean, tidy and efficient manner. Steve was polite, considerate and good at explaining the technical stuff.