Check me out - the rotary knob guy....
When you say it is playing up do you mean as you turn it you are no longer getting solid clicks that correspond to changes on the panel menus? It's a bit hit and miss, feels a bit loose, like the splines in the metal shaft no longer engage with the slots in the plastic knob?
If that's not the case I can't help, but if it is bite the bullet, join as VIP, download the instructions, order a replacement knob from the club shop and do the job before you go. What happens if you are away from home with the roof stuck up? The instructions are good. You need to be patient and diligent. Just take your time and have some confidence in yourself. Read the instructions thoroughly, make note of the bits that could go wrong, slip the unit out and fix it. First time around took me about an hour. Second time 20 minutes. Third time about 10 minutes.
Torx are a type of screw head requiring torx drivers and you can buy the latter for a few quid online.
Tip - once fixed keep the tools in the van. Mine worked for a while but the centre 'push to select' stopped working. I have no idea why. The roof was up. I was stuck. I was by the Norfolk Broads but had the confidence to strip it out, reposition the replacement knob and reassemble.
Worked for a while then same thing happened again, this time on way to France. I stripped it in a motorway services and this time left the button on the glove box. We broke a set of tweezers in two and keep one in each front door pocket. They fit the slot on the shaft allowing us to rotate and push to select.
Not the most elegant but nothing to fail now. I am tempted to file the edges off my replacement button so it can be fitted and removed without stripping the unit. Not done that yet though. Or maybe I should ask to return mine for a replacement with the club shop. Hopefully you will get a better result.
If it's the rotate to select issue don't wait till it breaks and you are stuck with an elevated roof and no easy way of carrying on or getting home. Don't hand your wallet to VW. Have a go at fixing it yourself before it breaks entirely (it will). A few of us here have managed just fine.
Hope that helps.