If you check back in to your account on the shopping portal a day or two after purchase and then click your name / avios balance in the top right hand corner of the screen, this will bring up your purchase history and you should see the purchase as having tracked. If it hasn't tracked within 5 working days then you can submit a claim via the 'contact us' link at the bottom of the page. You'll need an order reference and a PDF or JPG of your receipt to upload. I've only had to submit a claim two or three times out of hundreds of purchases and BA normally respond within a few days to tell me a) they've added the purchase to my history or b) I've been stupid and not read the T&Cs properly.d

As an example of tracking speed - I made four purchases yesterday and they've all tracked today.