ok here goes.
will give a recent history of my experiences with agencies. about 7-8 years ago I got a job through an agency. Great stuff had a job for 14 months then left. When I left I didn't think through travel arrangements for new job so tried to get another job but not easy as just hitting recession. I was extremely lucky to get back to back short and longer term assignments in central government for the next 2 years, all paying very well. I had a friend who was a recruitment consultant who helped me, had clients and was honest. Some of the other agencies literally couldn't care less… and at the end I was earning about 8GBP as switchboard operator for courts service in London.
I then got a perm job where I've been for almost 5 years. After a year I decided to use agencies to see what else was out there, had 2 interviews, didn't get them as not enough experience or what I was after but good interview practice. A year or 2 later I also had interviews through small one hand band agencies all of whom came to meet me before the interview. One place had an internal candidate who was the obvious choice (due to being insider) but it was me and her. The others various queries due to either wrong fit or not enough experience. But again I wasn't overly bothered. My field is specialist (legal secretary). Also these days it is a lot harder to get a job as more applicants for fewer roles.
Recently I was put forward for a job by an agency for a difficult company - I had 3 interviews (3rd was a half day test) and I was treated appallingly e.g. the man due to interview me had gone to a funeral when I got there, the man giving me work went into a meeting with no word of he was doing this, and the other women there were extremely unfriendly. I walked out.
2nd agency I was due to meet in Mayfair - I turned up for a potential job and the man due to meet me wasn't there, he was off sick… on ringing his office and speaking to a colleague my name wasn't in his diary!
I work and live in SW/SE London but its a trek getting to central London and also about 7-8GBP extra on oyster card not to mention taking time off work to see them.
I've met a consultant in a mini skirt who looked over my CV dismissively then said she just had a contract job - I emailed her boss as I was annoyed.
I also was put forward for jobs where I wasn't happy going for them Team Sec (not really agency fault or company's but could be clearer). The last time I complained to an agency who'd contacted me again about work I was given the 'brush off' by them.
The other week however I was offered a job. I got the interview through an ex agency worker who was working for a solicitors/accountants firm (new situation apparently) they'd seen my CV on linked in, put in my work postcode, had a brief 15 minute interview by phone, invited me after work for interview and offered me the job. They've also asked me to recommend solicitors working for them.
The thing these agencies don't get is I have a very long memory and will remember the rude/unhelpful ones and remember the smaller niche ones who are good. also in my new position I work in same dept as directors PAs (I am one) and near HR and I will not hesitate to tell them about agencies not to use should they ask. I also have a business idea for recruiting.
I've also noticed in past 6 months about 3-4 or more legal agencies springing up offering work but often they have same vacancies and are competing for work.
Yes I know some recruiters are sales people, I know they have targets, I know candidates often have rubbish CVs or don't turn up to agencies or for interviews but I am not one of these candidates.
anyway rant over - I'm sure I could be more concise, considered etc but on the whole the big agencies are rubbish.
So yes OP I feel your pain. In my experience I'd target companies HR depts themselves or use smaller agencies. Linked in can be useful if used well.
I myself hope the legal agencies who've sprung up will go bust soon…. as I certainly won't recommend either to my legal sec friends or other legal firms (and it's a very small legal world out there!).