I usually get charged when I owe £500 (I'm only a small advertiser so this is usually once every 2 weeks), but I haven't been charged since 24th March despite there being no change in my ad spend.
The difference from what you've seen is that the accrued outstanding amount does show on the account tab, they just haven't charged me, but it would suggest that all isn't 100% in the billing department (hell, why should they be any different to the rest of G!?).
Anyone ever had a problem with credits and charges not showing on the my account tab.
I usually get charged when I owe £500...but I haven't been charged since 24th March despite there being no change in my ad spend.
Issues such as these will always be best be addressed by the AdWords support team directly, as a look at the account would be required to troubleshoot. For this reason, I hope you'll contact AdWords support if you have not already done so.
That said, my apology for any inconvenience caused.
AWA