When you’re nipping things up, are you removing the collet and the tapered washer, then nipping the axle up and refitting the collet/tapered washer or just nipping up the collet bolt?
If you’re just nipping the collet bolt up then you won’t actually remove any of the play in the axle (that is absolutely normal for a VPP bike of that age and once removed will be sorted for a good while).
It works just like a headset. The collets are like the stem clamp bolts and the axle is like the top cap. You need to undo the clamping provided by the collet/stem and nip up the pre-load with the axle/topcap before locking off again with the collet/stem.
Hope that helps.
If you are doing the former and nipping the axles as well as the collets and there is still play coming back that quickly then you definitely need to pop it back to where you bought it as that is most certainly not right.