The present power adaptor feeds a VM modem Type 256V2 - that's what it says on the bottom of the unit - so maybe it is compatible with the Hub 3.0. and that is why they did not send another?????
The DOCSIS1/2 legacy Ambit (or UBI) 256 SACM PSU is probably rated down at 1.5A (or less) so even if the DIN plug fits the SH3 (my boxed samples are in my museum/attic so I can't easily check) then it won't have the 2.5A rating sufficient for the VMDG505.
I'd urge you to follow Ben's advice and ring say UK Retentions to (re)dispatch you correct SH3 PSU as the SH3 should/must have an accompanying PSU and even if they're now sending out refurb units w/o adequate QC/QA checks then the omission should be flagged/addressed.
Regards Tony "Life is a Binary Inspired Turing Computed Hologram"(don't PM or @Mention me - in case ignoring you offends)