Hang on a second. Despite not having a ring, you must think that 3+minutes to get hot water in the kitchen is not right when the boiler and cylinder are located on the same floor.
With all due respect, the builder's plumber came round and did a survey on the house before they quoted for the job and our requirements were discussed with them. I never said "at the moment it takes around 20seconds to get hot water in the kitchen and rest of the house but please take thousands of pounds of my money and extend that time to 3+minutes".
As for the ring, the builder said to me "...As I said it's not really required." I have this on e-mail and will use it in court if it comes to that but I am hopeful this matter can be resolved without having to go down that road.