Have a 2008 Golf Mark V TDI owned since 2013.
It has been a great car except for the electronic door and boot (hatchback) locking modules. Have had to replace all door modules except driver's. The boot problem was due to broken wires in the loom caused by the flexing during opening and closing. The replacement loom had more robust wiring (presumably because VW recognised a design fault). Went through fruitless exercise of trying to get some compensation from VW Australia's - wait for it - " Customer Experience Ambassador"!!
Seems the above problems are common in the Mark V's noting the number of posts on Google etc.