I'll add my name to the 'victim list'. Just contact BA, they will talk to Avis and you will get a refund.

I've never had the issue in the UK but it's all too-common abroad (I assume due to currency issues). Usually the overhanging charge just never shows up on my credit card but in about 10% of cases it does and I contact BA to get it wiped.

It's not a BA issue; I have the same issue when booking directly with Avis and it's simply infuriating.