I've had only one positive experience of the DVLA.
At one time I had two cars where the Road Fund Licences (I'm not quite old enough to remember when the tax was spent on roads) expired at the same time.
Both renewal forms arrived in the same envelope!
The second car is somewhat elderly, and, although the paperwork has progressed through old-style logbook, through V5 and then to V5C, the DVLA continually have problems dealing with it. At one point the "VIN" written down at the MOT testing station didn't quite match that derived from the Logbook. Obviously the same vehicle to anyone with Common Sense, but not to the DVLA. I took copies of everything, including pictures, to their local office for them to put in the internal mail. I got a tax disc while I was there (built before 1973, so no charge) without problem, but they lost the package, resulting in another threatening demand from Swansea.
Having resubmitted my documentation, Swansea sent me another V5C.
The following year, I went to the post office to get a tax disc. Having learned by now, I have everything scanned, including the "receipt". Six weeks later I get a demand from the DVLA to return the disc. Apparently the post office clerk was in the wrong for copying the taxation class from the V5C onto the disc. The DVLA had incorrectly changed the class on the V5C from "Historic" to "Not Licenced", and were complaining about the fact that I, and a post office employee, believed them. I sent off the scans, but refused to send the disc until I had a replacement (and yet another V5C).
I'm glad that these days I don't have to show a disc; I just have a reproduction of one from when the car was new. In those days everything was dealt with in person at a local office. Remember that "Handing in on the first will not do"?