Hello Daniel,
Thanks for joining and posting your plea.
Stop/start issues with a 5 year old vehicle?
Typical battery issue, and possibly below par on the cold cranking current parameter.
You could get the battery’s efficiency checked, but that check would need to be ‘sophisticated’ as opposed to a simple ‘% efficient’ test.
If you are going to replace it:- I always buy Varta/Bosch (original equipment suppliers) but only to their 5 year warranty grade. I buy on line from specialists such as Battery Megastore, Tayna - and there are more.
The battery will need to be coded to the car once fitted.
Kind regards,
Gareth,
p.s. All above, assumes the battery is the original.