Ignore my last post. Once I'd looked at a full size version of your picture I saw the pipe with the splits in was the one behind what I thought you were talking about.
I believe it is the pipe shown in the diagram below. You can only get this pipe as part of a complete assembly which is number 18 in the diagram.
While the part number is shown as
06F133781D, in the part detail it states that this part was superseded with part number
06F133781L on 1st July 2010. Listed at 27 Euros (which equates to just under £24 at current GBP exchange rates). However, looking on eBay I see brand new ones listed at around twice that amount so probably best to get a confirmed price from Dave at Sere Motors.