Boiler on the blink, help needed :)

[sinto607276]

Ahh well another day.....
After replacing the prv and getting a tad wet I left it last night and woke up to the pressure being at zero.
Thought I'd try and top up the water using the filling loop, heard some water go through and pressure went up a few red lines but not much
So looks like I'm on the blower to a costly repair man to come and sort it