OK now you know the servicing was "patchy" you will need to check / replace all the other service items that have probably been missed.
Start with ALL the fluids i.e. oil, screen wash, brake / clutch and gearbox. Also check the power steering fluid. Then things like the cam belt and water pump, thermostat and temp sensor with the coolant change. Air oil and fuel filters etc.
Then it is the routine of checking the battery, alternator and belt including tensioners / idlers. All bulbs and fuses, brakes, tyres and importantly the remote keys and replacing their batteries. You do have at least 2 fully working keys????