Botched boiler job

Hi all! I am very proud to be a part of the plumbing community on reddit as it's helping me with my current apprenticeship so much! I had a look at some work a plumber had done as we had a leaking PRV discharging from outside the property. Apparently the plumber fixed the leak (leak is still continuing) and upon my inspection I saw the copper to plastic coupling on the flow pipe that has been attached and most dangerously the earthing wire has been cut and not fixed to the flow pipe. I found out there was a charge of nearly £300 for this work that to me isn't safe, poor workmanship as well as having the initial issue still ongoing. What do you all think? Are my suspicions right?

Can I/How would you put a utility sink here for homebrewery cleaning? Could we tie into the laundry drain coming from upstairs and add a vent to above the trap? Not going to DIY just curious about the scope of the job before getting quotes.

Black dots in overflow hole

Came home from holiday to find this in the sink we installed 2 months ago. Unsure what it is. For what it's worth we have a water softener system in the house? Help please identifying it!

Toilet Crack -Monitor or Replace

Think this crack has been here about a year, maybe longer. It spans from where you can see her down into the inside of the lip, but not the exterior or interior walls of the bowl. I've read some horror stories on here recently regarding cracked porcelain, so now I'm leaning towards replacing the bowl. Just wondering if this would be an over-reaction on my part.

Does this look right? Too many turns?

Sewage smell from patent kitchen sink

I noticed our kitchen sink draining slower with a foul odor, so I removed the p-trap and the pipes attached to it, as shown in the red circle. There was a bunch of gunk and oil residue. I used bleach and a hose to clean it and put it back. After only 2 weeks I noticed it draining slower and water sitting in the tailpiece that connects to the drain. I removed the pipes again, and water was coming from every slip joint nut that I was loosening, instead of just from the p trap. This time I tried cleaning the inside of the waste arm that goes to the vent pipe as shown in green circle. I had to use a cloth as there was a lot of oil residue. I also noticed a slow drip of water coming from this waste arm while it was disconnected. After putting it back together, it drained fine. However, there is now an awful sewage smell emitting from the sink. There are no clogs within reachable distance. I thought maybe I put it back together incorrectly, but it looks the same as in the image. I live in a condo townhouse, and management told me to get a plumber. I think I found the vent pipe on the roof, but I can't reach it to see if it's clogged. I think our toilets, showers, etc are okay. Advice?

Is this an acceptable fix for main line to house?

How would I move these pipes?

These pipes are in my basement and are connected to hot water radiators throughout the home. Clearance is about 5.5ft to make it under them cleanly which really shrinks the room. Is there any way to re-locate these pipes?

Hot water flows slowly on a single sink in my house

The sink in my downstairs bathroom, which was an addition by a previous owner has unusually slow hot water despite the tub 5 ft away getting the(great) normal city pressure we expect. All I can think of is this corrosion on the valve has worked its way into the pipe and is the cause of low water flow. The connecting pipe from wall valve to faucet is new and I made sure no obstructions on that since turning off water was easy. If that’s the case, how would a plumber fix this and how to fix it so it doesn’t happen again?

Real Fact (heil spez)

A child’s perspective >