Finding Legal Leverage As Sub-Contractor?

Arthur Rabatin writes "We are software developers in London, UK, and get most of our internet related business through advertising agencies and design agencies. The standard arrangements are that the agency is _our_ client (contractual counterpart) and they deliver our software to the client/end-user. Although we typically know and talk to the end-client [the agency's client], we have no contract with them directly." Read on for why this leads to problems, and a plea for help in clearing them up.

"Our problem is that more often than not, projects get delayed because the design company can't agree with [their] client on the visual aspect of the site; although the functionality is often better defined (we write detailed specs), because the project is held up, the [end] client does not pay the design agency and hence we don't get paid -- often not for months. This despite we (a) are not able to deliver only because we do not get the HTML stuff from [our] client to actually put it up or (b) we do actually finish the software but end-clients refuse to sign off because 'the site' is not finished.

How do fellow programmers in similar position handle such a situation? What would be the best way to structure a contract so that we can't be denied our (IMO) fair deal? To some extent shall we accept our client's (the design agency) 'difficulty' they have with the actual client? How do you deal with situations that you need clients [of our clients] to sign off specs but the design agency just delays things because they don't understand it and think the colour of their submit buttons is more important than the software behind it?

As we all know, even if one has every legal right to do so, one can't just sue every client ( ... that's an idea :-), but we are at a point where we are putting our own business at risk.

Please help!"

Phew! -- I hope I've corrected followed which "client" is which with my brackets above. Does anyone have good advice when it comes to this kind of multi-tiered I'm-not-responsible business dealing?