Hello, my name is XXXXX XXXXX I will try help you with this.
Can you tell me the year, engine size and if petrol or diesel.
Is this the first time you have bought fuel from this supermarket?
I would doubt that is your problem
Has this only happened since the service?
Did you get new spark plugs fitted?
I would say most likely fault is with the crank sensor.
And quite easy to fit. Take about 15 mins max
Does the engine start easy when cold?
Does the spluttering feel like it is misfireing
First I would make sure you did get new spark plugs at the service. I would also check the ignition leads for signs of misfire damage. I would next remove the crank sensor and make sure the tip of it is clean. They are magnetic and can get fouled up a bit over time. I would also check the throttle body was clean and not sticking.
You could also try using a premier brand of fuel. They do make a difference but supermarket fuel isn't as bad as some people say.
Please remember to rate my assistance.