What the problem with my Wickes Combi 82 boiler?

Ive recently had british gas out to carry out one off boiler repair. They replaced the Thermostat and diverter valve and boiler has worked great for 1 month. The boiler has started playing up again intermittently working. Sometimes we get heat & hot water other times the boiler kicks in then goes off. Could this be the same part that needs replacing.

Thanks in advance