And then, if the plumper requires it, take the plug off again until an
electrician can make the final connections. I would have expected any
plumper to have done this, unless he is willing to return at your
convenience, and for free, when you get the electrician in.....

And why should he return for free?? is the plumber running a charity?? No
his time is money, so maybe the oOP should have arranged for a suitable
supply adjacent to the pump prior to installation. Don't expect the
plumber
to do some thing for nothing or you may not get a good quality job.

He is refusing to test his work !
The plumper is refusing to connect up the unit, it wouldn't matter if there
was an electricity supply to hand, in the words of the OP "he has said that
he does not do electrics", so he (the plumper) should either arrange for an
electrician to attend or return when an electrician will be present - after
all the electrician 'might not do water'...

A fair day's pay for a fair day's work.

Very true, and a fair days work for a fair days pay !

The plumber has given the customer notification prior to the job being
started that he doesn't do electrics. If the customer is unhappy with
this then he has ample opportunity to discuss this matter with the
plumber. If the customer wants the pump working when it is fitted have
the electrician wire the pump prior to final fitting and testing or
make the final connections when the plumber has fitted the pump.
If the plumber would have turned round after the pump was fitted then
I could see there may be a problem.


SJW
A.C.S. Ltd.