Thanks xelawho for the updated script using classes, that should work fine now.
Your question about the points being worth 5p - that's 5p each for when they're spending their accumulated points, so they get a point for each £1 they spend (ie. 20 points for £20 spend) and that works out as £1 (20 points x 5p each) that they can then save on a future purchase. That's basically how reward/loyalty points work.
If there was a way to show that as well then it would be perfect.
Sunfighter, I can't do it that way as I'm not building the shop from scratch, it's on an ecommerce platform and I don't have full control over things like that. But I appreciate your help.