Looks like a common problem...I had to phone customer services to get them to enrol the card in the membership rewards scheme, but supermarket shopping done over the weekend is showing with no bonus points, so I suspect no 20,000 points would show up when I hit the £500 trigger. I spoke to customer services again this morning, and they assured me that the bonus points appear at a later time, and that the 20,000 points would appear when I spent £500. I wasn't convinced, and was put through to Membership Rewards. The chap I spoke to there agreed that the supermarket spend should be showing the bonus points, so he has sent it to the appropriate team to action.
Moral of the story: don't be fobbed off my customer services, and speak to Membership Rewards!