Tax disc missing & car boot & door open

So, I returned to my car and had a police warning saying my tax was invalid which was surprising as I'd only just paid £260 for a new tax disc less than a month ago!

Anyway I looked in my tax disc holder expecting to see a misprint or something on the new one, but the old tax disc was there, and the one before, just not the new one. Now I know I put it in - I've still got the perforated slip in an envelope.

I phoned the DVLA who confirmed I was taxed until next June and that it would only be £7 for a new one. No problem.

But.......

What's playing in my mind now is that around 2 weeks ago I passed my car one morning and the boot and back door were open. I checked everything and all seemed in order, CD's, sat nav etc... still there so I thought nothing of it other than my boot was soaking wet as the weather was cack. I figured I might have had a daft moment and pressed the boot release button, but couldn't explain the door.

Now with the missing tax disc I'm thinking my Reg might have been cloned. What's the chances? The car is a 2002 B6 A4 - are they that easy to get into without visibly damaging anything?!

Yea i've had the car 3 years now and got full set of keys so no need to worry about that, besides the guy I bought it off is a member on here and a nice bloke.
I'm probably being paranoid and the tax disc has blown out or something and the open boot incident was me sitting on keys!...

Yea my first thought was that the tax disc had blown out or something - it's nowhere to be seen in the car. I found a few parking tickets stuffed down the dash and passenger's seat rails.

I thought the same with the boot. You have to manually press it to open it even a little bit, which makes it more concerning that the boot AND door were open.

I reckon somebody's had a rummage around but it's strange that nothing else went from the car. There was about £1k worth of surveying equipment still there. Camera, tool bag, laser tape, levelling equip. Nothing gone!

I don't know what to think. The DVLA have told me to log with police anyway just in case I get a knock at the door for toll charges or petrol pump fraud.

Yea will log it with the police anyway just in case - better safe than get a knock on the door