Plumbing conundrum

[BinRobin2]

Trying to resolve couple of plumbing issues at home. Spoke to couple of plumbers who are eager to do what I want done, as opposed to advise on what is the right thing to do. I want to be better informed to take a decision. Here it goes:

The property is on a gravity fed system (cold water in the loft, hot water tank in the airing cupboard).

Issue 1- Upstairs bath room is fed by a shower pump with a manual mixer shower. While taking a bath, if water is used in another part of the house, water in the bath turns cold.
Issue 2- Downstairs shower room is fed by an electric shower. While taking a shower, if water is used in another part of the house, water in the electric shower get scalding hot.
Issue 3- Low hot water pressure in the kitchen, bath room and shower room sinks. Cold water pressure is fine. Not high, not low.

Solution set A:
Issue 1- Replace manual mixer shower with a thermostatic mixer shower
Issue 2- Replace electric shower (cold water supply only) with a thermostatic electric shower (cold water supply only)
Issue 3- Install a hot water only pump in the house
Supply & installation quote received- £1200

Solution set B:
Issue 1- Replace manual mixer shower with a thermostatic mixer shower
Issue 2- Replace electric shower (cold water supply only) with a thermostatic electric shower (cold water supply only)
Issue 3- Remove the shower pump. Install a whole house pump (cold and hot water feeds). Re-route pipes for bath to the whole house pump
Supply & installation quote received- £1600

Solution set C:
Issue 1, 2 & 3- Do not replace mixer shower or electric shower. Remove the shower pump. Install a whole house pump (cold and hot water feeds). Re-route pipes for bath to the whole house pump.
Supply & installation quote received- £800

Any thoughts from anyone on what approach should be taken to resolve the issues? Main concern is that my disabled elderly dad and my toddler son use the shower/bath and the sudden spike/drop in water pressure is turning a bit of a nightmare.

Thanks all.

 

[Wayners]

You got an old 15mm pipe to house?
Neighbour had a 22mm polypipe fitted replacing 15mm copper that burst. Amazing flow and pressure to the house now. I'm keen to replace ours if I could afford it as a luxury.

To answer. Not my area but the whole house pump sounds ok. Power showers in the 90s seemed to die a death though. Too much like standing under a jet wash I guess. House pumps seem to work better though keeping flow rate up from what I've seen.
Thats all I know...Not much help though sorry

 

[Murdochcat]

Sounds like your electric shower isn’t fed off the incoming supply which it should