I believe most installs go well and there is no reason for them not to, providing “properly” qualified installers who take a bit of pride in their work fit them.
Sadly when it does go wrong, it really does go wrong, which could be down to many things including people jumping on the band wagon, solely becoming part P qualified, which in the scheme of things isn’t a fully qualified spark, similar to whats happening in the heat pump industry.
The other grey area is the scandalous cost for non standard install work but, when Motability pay below the going rate and by the time its passed to a contract comany, along with the possibilty of been contracted out again, theres not left n the kitty to pay the installer. This explains the higher costs for non standard work or delays getting the charger installed, due to the spark’s own work taking priority.