Issue with release of water/steam pressure

I have an Ambiano Expresso maker, model - GT-EMG-01-UK, and I have an issue with it. When I have used the Steam Wand to warm/froth the milk and turned the and off the machine will not go back to the hot water/ brewing coffee mode. I have to turn the machine off and wait for several minuets then turn it on again for it to work properly. The warrenty ran out on 14th April this year.

Can you help with this issue please.