My sister is going to her (wanker of a) dads wedding soon and they have kindly picked her dress for her

http://www.longtallsally.com/tall/dresses/above-the-knee/structured-ikat-print-dress/multi?category=f-013_dresses

Now she needs some shoes to go with it.

Her stats - 6 foot tall and size 10 feet...............help!!!!!!!!

ohhh for her height i would suggest flat shoes !
but thinking some plain black heels would look great

I think black is probably the best bet, pumps or a kitten heel.

There are nice ones on that long tall sally site but pretty expensive and I dunno if your sister wants to pay £65-110 for a pair of shoes?

Ebay is another option. I did a search there for ladies black size 10 and a few came up, most have bids on but so depends whether you mind them being second hand and waiting a cpl days to see if you win.

Why did they pick her dress? Is she a bridesmaid type person?

No she's not a bridesmaid because they didn't want my other sister to be a bridesmaid. They've done nothing but poopoo the dresses that she picked herself cos 'it's not suitable for a wedding' or 'it's too bridesmaidy' - $%&^*(& pair of twats