OK, I know it's been a long time, but I've finally had my Streetguard trousers repaired by the fine folks at Schöffel. I needed the waistband zip that connects the trousers to the jacket replaced, so I reasoned that getting the manufacturers to do the repair would be safer than entrusting it to someone local and ending up with leaky trouser syndrome
The cost of the repair itself was relatively cheap (for the amount of work involved) at €42, but with carriage charges both ways and the £20 that my bank charged me (

) to make a SWIFT transfer, the whole deal came out nearer £80. Still cheaper than a replacement pair of trousers though.
BTW, Lodenfrey (the contact given me by BMW UK) only repair leather clothing; all the textile stuff is repaired by Schöffel.