We do work for several property management companies. Most are big nationals. Not for window cleaning I should say, but another cleaning area of the business.
Never, not once, have we been asked to pay, to supply them with a service. If any did, I would tell them to sod off. Any legit company won't ask you for this. Its a bit like the talent agencies asking for 'commissions' to add people to the books (isn't that now illegal?).
The only ones you expect to pay for are the likes of trust a trader, who are nothing more than a glorified directory.
Personally, I would walk away and look for work elsewhere.