Just to add my two penneth!! - I've been through this whole routine with the pedal covers for by Brera:
I first bought the 'full' set (including footrest) via ebay from a dealer in Doncaster (Fiat dealership, but also supplies Alfa parts) and found that as mentioned above, the footrest was for a LH drive car so was way too big and the wrong shape! I got a refund for this and fitted the pedal covers myself - not an easy job, having to drill holes in the steel pedal plates with limited access!
To get the matching alloy footrest, I simply asked Mango's to order me a Brera 'S' replacement - job done!
The footrest simply replaces the standard plastic one and takes seconds to fit.
The problem is, not all parts dept people are fully aware of the 'S' set up i.e. all the specific upgrade parts for an 'S' aren't on the usual parts sytem, but are listed on a seperate price & code sheet.
Just speak to your preferred dealer, explain the situation, order a Brera S footrest cover, and get them to post it out (couple of quid max), and Fanny's your Auntie!!
......................now can I bring myself to pay £60 for the prodrive mudflaps??.................