I went along to the easiest VAG dealership to buy one for my wife's VW Polo 1.2TSI 110PS, which was a Skoda dealership, they had none in stock, and on back order at the UK warehouse, this was said to be due to change/revision of that part, so maybe it is finally getting made to survive as long as the exhaust.
I found one of the size I needed on ebay for cheaply, so grabbed that - for future use!
To the OP, if you are just going to buy a new joining section, it does come fully assembled complete with its own clamps, last one I changed, on a late 2009 Ibiza, I just harvested the clamps of an aftermarket one and left the original sleeves on the car - same for my 2000 VW Passat 4Motion many years ago - the easy way out!
Ideally you wait until either one clamp spilts and the other will be almost "gone" so will give way if you abuse it, sounds like a bit of a gamble, the sleeve on my wife's Polo did shock me as it is only 6 years old, I "tapped" it with a hammer and the rust fell off, but it will probably last another 2 winters, my I am now prepared with a new sleeve, though it is stupid just to ignore that and wait for the rattle or increased exhaust noise from a loose joint.