Adam, PM me about this.
I've been watching this thread and had to make comment.
We had £250k's worth of July's revenue withheld on an 'AIT retention'. To be fair O8 are fighting it for us - but not holding our breath.
We had quite a lump in February as well, plus a whole number range barred from the network to add insult to injury.
Like yourself we've been in the business for quite a few years and this can certainly hurt - especially the smaller start-ups who are putting a load into advertisng etc..
Glad someone has had the balls to speak out about it - maybe a few more SP's will come out now and we can launch some sort of class action lawsuit after comparing notes ?