Many thanks for all the helpful replies and comments…very much appreciated.
The dealer in question is Rich Tone Music, located in Sheffield.
Problem is, I live in Luton, so I can’t really turn up at their premises.
Paid by debit card, so no protection there.
I have phoned them, but was told someone would get back to me the same day.
A local guitar tech has confirmed that it’s the pickup that’s faulty, but is reluctant to do any work because of warranty issues.
I’m actually in my 70’s, reasonably poor health (completely my own fault due to a lifetime of pro bass playing!) and still working about four nights a week.
Once again, very many thanks to all.