Help with lighter socket replacement

Hi folks,

Would anyone be able to help me with my roomster's lighter socket?

I've had the car since November (and I've fallen in love lol), it's my first car, I'm also in my 40s and don't have any car tinkering family to ask about this stuff!

The car came to me with a faulty cigarette lighter which the dealer was supposed to replace. It's the lighter bit not the socket that is broken and socket actually worked fine as a charging socket. They "forgot" and instead ordered a replacement socket and said it'd be easy to replace.

I didn't fancy messing with it but when my seatbelt needed fixing I asked the garage to replace the socket at the same time. Garage came back saying the replacement wasn't the right kind so they didn't fit it. I asked them to put the old one back (seeing as it worked fine, was just a bit tatty) which I thought they did.

Turns out they put it back in but didn't connect it. Found this out trying to use my tire pump. And it seems maybe the boot socket is connected in series or something because the boot socket also isn't working. 

So today we had a look to see if it was doable for us to fix, opened up the panels and got the plug back in but it's still not working. Is there something else they would have disconnected? Looked at the fuses and I *think* the one supposed to be the sockets is in (I looked just in case it was obviously missing).

Is this something that is possibly an easy job if I can be guided? Or should I deffo get (a different) garage to look at it?

I am obviously new to understanding the car, but I am fairly competent with practical things. At least I'd appreciate any advice so I can make sure I give the right instructions to get a garage to do the job properly!

And, sorry for the long question, if anyone would be able to easily double check I'm ordering the right replacement bits I'd be super grateful. I feel like I got taken round the houses a bit with the parts diagram on here -

https://www.lllparts.co.uk/product/1K0919309/1k0919309-genuine-vw-audi-2

I'm trying to get the socket and the ring surround clip as I can see one of the clip/flange bits is snapped off. I figured I don't actually need the lighter unit as it's never going to be used. 

Thank you so much for any help!