About to fall through

We are in the 6th month of the process so our mortgage offer is about to expire. We have asked for an extension on our mortgage offer which has been rejected. We have till the end of the month. The top of the chain is causing delays but our buyer (cash no chain) and our vendor are ready to go. It's the chain onward from that that's not ready. The estate agents have been completely useless and impossible to get ahold of for the entire process. Despite us updating them last week that there will be no extension to the mortgage offer we have still been given the run around. We are at the point where we believe we likely won't be offered a new mortgage deal under the new interest rates. We had to try a few lenders to get one to agree to lend to us in the first place 6 months ago. We have communicated this to the estate agents but still they just seem not to care. Don't answer the phone, don't call back when they say they will. There was talk weeks ago of our vendor considering breaking the chain by going into temporary accommodation but we've asked for updates on that since and have been given no clear answer on it. We keep trying to get through to the more efficient EA we've been dealing with but it's impossible. It's always the other EA that calls us back and he is absolutely clueless. He sounds like a 19 year old that started the job last week. Often it feels like he doesn't even know what client he is speaking to and we don't know if things we discuss with him ever get passed along to his manager, the one we are trying to get ahold of.

We have our vendors phone number after we went and viewed the property a few months ago to measure up for a few bits. At that time we all discussed how useless the estate agents seem to be and swapped stories and it was clear some things were not being communicated as we had thought they were or just not at all. My question is would you contact them to ask if the estate agents have conveyed our current position or ask if they've even been asked to consider temporary accommodation. Not asking them to give us an answer but just check they've been approached about it in the first place.

If anyone has any insight or ideas on what we can do to push things along please let me know. If this all blows up we will likely have to stay where we are for a few more years and lose our cash buyer.