I work for a big multi national company in US. I have been working with them for almost 3 years now. Last October (8 months ago), they wanted me to move to a different location to work alongside a client, and offered to reimburse upto $15k in relocation bonus (including 6 months of rent). I have moved and used around $12k in total including rents for 6 months. Also, they offered to start a green card process for me and I have declined that offer as well and did not sign anything.
I recently got a better offer and I gave my 2 weeks notice, now HR calls me and says I need to pay back $20k of relocation bonus, and $10k for Green Card processing. I did not sign anything regarding the paying back of the relocation bonus and neither I was communicated verbally regarding that. I am not sure what to do now. I am not in a situation to pay back even the relocation. Any advice on how to proceed?