Misfire detected DTC

[Quattrodave]

Morning all,

Two days ago I had a very rough and not happy A8 (4.2 FSI). On pulling the codes I got P0024 - B Camshaft position timing over advanced - Bank 2. It also stated misfire on cylinders 5, 6, & 8.

I had only just left home so quickly turned around and headed back. After a few restarts the engine ticked over fine, I cleared and then reran the codes and all came up clean so off I went, 15 or so miles no problem.

Then last night it came back again, only this time misfire on cylinder 8 only and P0024.

Same this morning. rough as hell at idle but revs fine, no lumpyness or such when under way. There's a lot of clicking coming from the passenger footwell too, relay/solenoid type clicking - presuming these are linked?

In peoples experience would the above suggest that the camshaft solenoid in bank 2 need replacing, if so, how much are they and is it a diy job?

Thanks