Coolant leak

[TomH]

Hello all the photos i have taken are on the right hand side of the engine underneath. As you can see this certain coolant pipe has corroded and is leaking coolant i am having to fill it up every other day so it is draining pretty fast. Hopefully the photos are clear enough for someone who knows what they are talking about to see which pipe/part this is called and if its a big/costly job to replace? Thanks for any help I appreciate it. 
 

This is on a A3 2.0tdi 2006 8P. Thanks. 

Edited February 1, 2022 by TomH