Hi Azeey, thanks for asking.
Yes, it's better than OK. My client phoned my agent and whilst I wasn't privy to the conversation, he basically told him that they were taking the **** and that they either reduce their margin or lose all future business with that company. This agency place a lot of contractors with my client, so unsurprisingly they have upped my rate.
And in the words of the client: "we'll be keeping them on a pretty tight leash from now on"
Thanks everyone for the fantastic advice