Weekly bus p/oyster card cost?

I haven't travelled on public transport for years but now I have to. Years ago I use to buy a buss p for about a tenner a week & it gave me unlimited travel in London. Now it's an 'oyster card'. Can someone please tell me, is there an oyster card that does the same thing? A weekly oyster card that I can buy & I get unlimited travel? I'd only need it for zone 6. I can't find any info on their website. I know I can get a pepaid one, but my question is about a weekly one. Thanks