vokera unica 28e no hot water?

My boiler and central heating system were installed 5 months ago. No problems until three days ago when we woke up and the heating hadn't come on but we did have hot water. My boyfriend bled the boiler and now the heating works.

Now the problem is that we have no hot water. It came on briefly yesterday but not enough to fill a sink. The boiler acts like normal, as though it is heating the water. The pressure is currently at about 2, I have checked all the radiators and none of them seem like they need bleeding. Any suggestions on anything we can do? If not should I call Vokera or the person who installed the heating?

Many thanks for any help :-)

Natalie