B&M are short for Brick and Mortar, so internet short for a physical shop.
The A1 Sandisk card should be fine, so you have been unlucky with yours,,,,, i am not quite sure if it have warranty on it for use in dashcams.
Many regular memory cards don't cover dashcam use as they say its a extra hostile environment,,, and so it is. But nowadays you can get so called endurance memory cards, these are specially made for use in CCTV cameras and dashcams so they will have warranty for that kind of use, at least for 2 years which i think are the minimum offered by any of the brands.
In the previous years most of us have just used the regular memory cards, and often gotten a good long service out of those, and we did so cuz the endurance cards use to carry a hefty premium.
But this have now changed for the endurance cards, so they don't carry a premium price or maybe just a little one, i would for sure only go for a endurance SD card if i was to go buy one today.
Most if not all of the major memory card brands have one or more endurance model, Sandisks endurance card as i recall are white with black and a little gold writing on them.