Start with the fault
A boiler that has stopped working may need a repair, but the answer depends on what has failed and the condition of the rest of the system. Note the symptoms, any fault code, pressure changes, leaks and whether heating or hot water is affected. A proper diagnosis gives you more useful information than guessing from age alone.
Questions worth asking
Ask what has failed, whether the repair is practical, whether parts are available and whether the existing boiler still suits the property. Consider the wider system too: controls, radiators, pipework, hot-water demand and system condition can all affect whether replacement would solve the underlying issue.
If replacement is the better route
A new installation should be sized for the home and planned around the correct boiler type. Suitable manufacturer options can be discussed together with controls, magnetic filters, system cleaning and manufacturer warranty information.