The reliable way to hire a tradesperson

My neighbour has recently built a 12 foot wooden “office” over his side of our mutual boundary fence. Looks nice. However, he has now put armoured cable across the top of the mutual boundary fence to power it. Is he allowed to do this.

At the start of the project we were given a price of 5k and told no payment needed till after completion 3 days in, landscaper asks for 1.45k to cover materials and then to pay the rest in cash - I send it After the 3rd day he asks for another 1.45k to cover materials. I question as this is the second time he has changed his mind. Is this dodgy or normal practice?

Hi, ive just recently had 2 radiators removed for planned works to be put back on at a later date. The plumber removed them but since my hot water pressure has dropped significantly. My boiler pressure is at 1.5 bar. What could be the problem? Thanks