baxi boiler says dry fire?

boiler works but no heating or hot water. Baxi solo, Baxi man came, showed us how to do water pressure, but still nothing... he gave up said need expert in whole system. Said it was airlock in pipes!? Have bled all radiators. Pump circulator makes swishing noise and that's all! Not normal sound. Any ideas? Or should we just call an engineer and be done with?