HCL Technologies — Hiring process

After clearing an interview had a discussion on salary. At first they proposed the new salary and sent the salary break out also. But after 4 few days hr recruiter called and informed me that we can't afford to pay the proposed salary then i said that i am rejecting offer later after 1 week they called and informed me that we are ok with proposed salary and asked me to upload the documents. And finally offer is released with the pay which is less than proposed one. So i called and asked hr if that is the case why you have asked me to upload all the documents but he said that you will get revised offer by tuesday and just now i had call with hr but he said that we can't afford. I don't understand what is the issue. If they can't afford why they asked me to upload the documents and after uploading why they are saying like this..
I need clarification for my above query.