Can I file a lien?

I am a sub to a subcontractor. We did work on a job in August where we installed a miscellaneous metal job that the subcontractor fabricated. We billed the project to 90% completion at that time. The remainder of the job was to be ready in November for us to complete the final installation. When we returned in November, we found that the material was not fabricated correctly and we had to make numerous changes. Our field supervisor and the sub that we worked for, along with the GC, agreed verbally that the remaining work would be done on a T&M basis. It was clear that this was out of scope and would be a change order. We discovered along the way that the sub that we were contracted with was not very reputable but the GC rep said that he will make sure we get paid. We have had a good relationship with the GC, so we took him at his word, and unfortunately, our field super did not get it all in writing. We completed the work and submitted the invoice and now the sub is saying that they never authorized the work and the GC said that it is out of their hands because our contract is directly with the sub. The GC said they cannot pay us directly and subtract it from the subs' payment since our contract is not with them. They also said that we cannot file a lien because we do not have anything in writing about the additional payment for the CO. Do we have any recourse?