I have just moved into a house with a mira 88 shower which is connect to a
mira PPT3 shower pump. The problem is that the pump starts up (and keeps
going) as a result other taps being used (only sometimes not allows), it can
only be stopped via the hot bath or basin taps up stairs in the bathroom !

Having looked at your installation instructions it appears that the
installation was incorrect. As the PPT3 is located above the shower in the
loft, its cold feed is directly from the cold water tank about 30cm above
the pump and the hot feed is from the hot water tank located in the bath
room. There is not surrey/essex flange fitted and the output from the hot
water tank is taken about 30cm above the top of the hot tank.
Therefore I presume the other taps are causing the water to be pulled back
down the hot water feed to the pump.

When I run the bath/basin taps as small amount of air comes out with the
water !

So not being an expert but having investigated this my solutions appear as
follows:

1.Fit a pull cord switch to the pump in the bathroom, to enabling me
to turn the pump off when not in use. Does this cause a problem ? Also
enabling me to use the shower without the pump ?
2.Fit a surrey flange to the top of my tank therefore the feed for the
pump will be lower , therefore the water might not be able to be pulled from
the hot water pump feed.

3.Move the pump into the airing cupboard, lots of work !!!!!

My first idea is to do 1 and then may be 2
Any ideas welcome.