Baxi Combi 80E Boiler?

I have no hot water but I have heating. Radiators had to be turned down as temperature too hot. I tried to turn down termperature on controls I have in the kitchen (radiator in loft) but it made no difference even when I turned heating off radiators still hot. I haven't a clue how to fix this problem. Something not right with a valve or something. Can you help please.