Client changing contract terms? Wants more time without paying or helping

I have a client who was a an executive a top 3 tech company. I’ve taken her on privately for PR and speaking opportunities. I presented them with a contract where we provided data to execs at large companies, and offered to reach out and email companies for speaking opportunities on a commission basis. In our contract it clearly says we will pass on applications and opportunities, they will decipher those and work them out amongst themselves. If the gig is a good fit, they’ll book it on their terms. When a lead that we sent them turns into a booking, we receive that commission. Well now they have asked us to purchase a different set of data, which we gladly did to meet their needs.. and have reached out to those contacts.. but now those particular contacts are asking us to put together proposals, and fill out lengthy applications. When we originally started this project we agreed on 10 hours of bandwidth.. it’s now turned into double that with this new initiative.. I’ve asked them to take on the applications like we originally agreed upon but they keep responding with “oh well we will help you find an easier process, let’s define what that looks like” “you need to do x and y, to make this easier..” completely ignoring the fact that I’ve highlighted this wasn’t in our original agreement.. I’m thinking about finding a happy medium and saying well we will fill out simple applications while you all fill out complex ones, along with tailored proposals. I’ve tried hinting at that and they just seem to keep pushing the responsibility on us.. mind you I’ve invested about 4,000k into this project, it’s truly an investment, I believe in their mission because it’s a good one ethically and for my own roi I want to see it succeed.. but I’m at a spot where I need to stand my ground and I’m afraid it’s all going to fall apart. I feel like they are bullying me, and not contributing in any way. Do I flat out tell them this? When I do, I feel like they might pull everything and I’ll be out thousands.. I also can’t afford to set aside paying clients to utilize all my time to fill out these 30 page applications.. i just don’t have the resources. I’m in such a pickle. Please help!