My company hasn't given acceptance to my resignation mail

Hello sir, It is to seeking guidance about the situation I am facing currently. I was working with a company for the past year. Due to pandemic, the company was facing funding issues, which results in the non-payment of salary on time. Because of this, I was having financial constraints and months of dues. I knew the company will not clear the dues so I just wanted to resign, which I did on April 29, 2021. As per the appointment letter, the notice period was 2 months, which I couldn't think of serving at that time due to financial constraints. Serving 2 months will just add more dues to existing ones. So, I mailed my resignation email to the company with 2 weeks notice period, to assist the company in helping find the replacement. But, the company HR contacted me and told me to resign on an immediate basis, which I did. The company respond to my email and tried to retain me. But, when they realized that they can't, they didn't give acceptance to my email. Now, I have a joining on hold at a new company, due to the absence of acceptance and relieving letter. The biggest issue is, when following up on my resignation, the company is not denying acceptance but not giving it either. As you know, the relieving letter is very important, but the company deliberately stalling the acceptance. I need your guidance that what are the possible ways for me to get the acceptance and relief letter. What should be my plan of action?