Finally forced the issue today with that firm, stayed on the phone line until one of the managers decided to take a moment and speak to me. Told him not to insult my intelligence with his crap reasoning for not even notifying me that I'd been unsuccessful (I of course gathered that but after being promised some feedback I felt justified in being angry). Just slammed the phone down in the end because clearly they're cowboys who I wasted my time with.
Have left a scathing review online that I'll post below, I think it's fair all things considered and I hope it doesn't come across as too whiny.
Review
Awful dealings with this firm, they promise you communication and nothing ever comes. In my situation I applied for an office position and was asked to come in for face-to-face after passing several phone interviews. I agreed to this even though we are in lockdown (offered to do one over Facetime instead but this was refused). Went for the meeting in the morning and once finished I asked the two men I'd met with when could I expect to hear news one way or another? They specifically said "it will be by the end of today". After that I heard absolutely nothing. Zilch. Not even a generic email saying you've been unsuccessful on this occasion, that would have at least been something. Before long I of course gathered that I hadn't succeeded but still waited for some sort of contact because THEY SPECIFICALLY SAID that they would be in touch with me. Also, I think it's just common courtesy when you consider the fact I was one of only two people who'd reached that final stage (and was the first person interviewed).
I decided call them up after a week of waiting for something and could never get through to anyone. Tried for days, no one ever answered the phone. When I eventually did get through I spoke to a girl, she took my number down and said she'd tell her managers I'd called and someone would be in touch soon. A few more days, still nothing at all. I kept trying and eventually (NINE DAYS after our meeting) someone finally agreed to spare a moment and speak to me. His explanation was rubbish, all he'd say was "we don't give feedback" even though he was actually one of the men who'd point blank told me to my face I would receive contact the week before! Pathetic all things considered, clearly a case work-shy and pompous management. God help you if you have work done on your house by them and need to call their office to ask about something or to complain, I imagine they'll try their best to fob you off as well. I've honestly got no idea what their engineers are like, whether they do a good job, bad job, mediocre job, etc. Just I've learnt from my experience that their communication is truly woeful and the people in charge are very ignorant, they will utterly blank you until you force the issue (and then give you crappy excuses).
A lack of courtesy and breaking your word (with no apologies) says an awful lot about a firm I think. My advice, save yourself the hassle and steer clear.