Shoddy plumbing, shower not draining

[Dandelionrarrrr]

Hi. We bought our house three years ago and we soon realised there was a horrible eggy smell when we used the shower or bath.

The small bathroom has a freestanding shower cubicle and a bath. Some days The smell was worse than others. Tried unblocking the drains, lots of cleaning products. Noticed there was a crack on the plastic pipe that run on our outside wall (not the soil pipe, I think it was waste pipe)
DP replaced this pipe, and in the process had noticed the pipe work looked very bodged. It ran very flat and clearly wasn’t draining right, when we lift the pipe the plug hole on our shower slightly emptied. The plug hole is continuously full with a pool of dirty looking water

We are no plumbers but are really hoping to save money and get some advice on here. We are looking for a way of keeping the pipe higher. Is there a well known accessory to raise pipes to help them to drain. Or is it far more complex/expensive than this!

show us some photos of the pipe, trap, connections, plughole please

Hope this works.

I can't make out the route of the pipes, but they don't seem to have any fall on them. First rule of plumbing is that water runs downhill. It might be possible to route them better under the floor.

Does your shower waste have a removable pot inside?

Because of the picture up load limit I tried to make a collage.
The plug hole isn’t very clear but hopefully you can see the water inside it.

There is a pipe that runs along behind our toilet roughly 4ft long it then goes under the bath. I can explain the pics if you need it.

I don’t think the shower has a removable waste pot. Is there a way of identifying it? It looks like it’s meant to travel down the pipe and into the water waste pipe that runs through the wall and outside of our house.

luckily it looks like you have good access to the shower tray waste so it could be replaced if necessary.

It is supposed to contain water, which provides the seal to prevent smells rising up. The pipes however should be empty when they are not running.

Washing Soda (AKA Soda Crystals) as used in laundry and for keeping washing machines clean, is good for removing soap and grease deposits. Sold in supermarkets near the washing powder.

it is not the same as Caustic Soda which is quite a dangerous chemical.

If you are not keen on plumbing ask around for personal recommendations of somebody local. It's the sort of job a wrinkly semi-retired plumber would do. No need for a costly gasman.

Thanks for your help, really appreciate it.