ESL recruitment agencies for Saudi teaching jobs

Has anyone here ever heard of the allegedly American based recruitment agency Skyline Global, or the alleged UK based agency m2r Ltd?

I haven't found anything online indicating whether or not these agencies are legit, nor any other teachers' experiences with them.

I am currently corresponding with both & they claim their Saudi clients will pay top dollar ($ Protected content on qualifications/experience), provide free accomodation, free health insurance, transport allowance and round-trip plane tickets....however, m2r Ltd e-mailed me saying I'll have to pay £550 for a single-entry visa and only get $200 towards it (already there my suspicians were raised at the 2 different currencies and staggering high price for the visa), then he attached a PDF which actually had the logo of Skyline Global and in there it said a single-entry visa costs ~£34 and a multi-entry visa ~£85.
When I asked him why there's such a big difference in price and why do I have to pay for the visa, he "disappeared". I'm pretty sure he's not busy, because prior to this he emailed me 3 consecutive days in a row, now it's been 2 days and no reply.
Besides, it makes no sense to me if the Saudis can afford all the other stuff why they can't foot the bill for a visa which is probably the cheapest thing out of everythign they're paying for!?

As for Skyline global, their info was sometimes vague and generally not very clear at all. They haven't indicated whether or not they're happy with my CV, I'm not even sure if they decide or the actual employer, there's no indication of an interview and they state that the employer will decide whether or not to make contact before OR after the application process OR after arriving!
Sounds a bit dodgy for an employer to not be bothered to make contact especially if they're really going to fork out so much on salary and benefits!

Besides that, have any English teachers had any bad experiences in general with their employers concerning pay, anything in their contract or visas and leaving the country?
I'm quite apprehensive about going there alone and possibly having an issue and not being able to leave when I want. The British embassy have reasured me they WONT be able to help in such a situation, so you can imagine how much more comforted I am by that tid-bit of info.