Looking at how the MKII consumes bulbs it might be the case that the fiver ones from various motor factors are of inferior quality. Maybe the extra €2 in Applegreen was money well spent, only time will tell, I guess... Trouble is I have a spare from a motor factor in stock now 'cos I bought a pair of them when I last changed one in the MKII on 23/02/2022. In fact, now that I think of it, your man in the motor factors did mention more expensive (probably LED) alternatives... which I declined.