Had them say something similar to us a coupla years ago when we were having problems with our, admittedly getting on a bit, boiler. In the middle of winter.
Pipes were rattling, boiler cutting out without warning and losing pressure all the time- had about nine or ten visits, various bits replaced, told we prob had a leak under downstairs floor… Problem continued, ended up having to stay with in laws for 2 nights cos we had no heating and a new baby. Turned out a thermostat/heat regulator was gubbed, water was superheating and turning to steam hence the noise!!
Pita at the time but had them out at all times of the day, they were always pleasant to deal with and they fixed it eventually! They also gave us some free fan heaters to use.. Still come in handy for the garage!