Help identifying CVT gearbox code

Hi all,
Have just had the dreaded PRNDS dash lights start to say hello on our A4 B7 cabriolet (06) Only two instances in the last week but by all accounts this is a progressive problem that just gets worse so we'll sort straight away.
Managed to locate a company called 'ECU test' who will refurb or exchange the Gearbox ECU for a reasonable price and will put it in to my local Audi chap to sort this week. Any references would be good.

Main question surrounds the cvt gearbox code. Ours is marked HED and wanted to establish whether this is the later 7 piece cutch system or the more troublesome 6 plate system.
Car is mapped and am a little paranoid that the tinkering may affect the reliability. ECU is acceptable repair but total box would be a mare!

Any feedback appreciated.

Thought I'd update my own post as gearbox was fixed by my local VAG specialist MDM technik having got an exchange ECU from ecutesting.com, who incidentally were also most helpful. Not as expensive as initially feared, so used the opportunity to replace the suspension too.
Bilstein B12 kit installed which we're very happy with.
Roof is playing up now though so am starting to get a little disenchanted with the car generally.
Will be using it as my daily drive from September as my wife has ordered a new car. Wanted to upgrade further but a bit reluctant to spend any more on it until it's given a solid year's service without further fault.