Issue with giving relieving/termination letter

I'm a BE graduate and worked as a dotnet developer in a company where I have signed in contract form(office letter pad) for 3 years, I joined here as a fresher(joined 4 Nov 2019) , now 1 year got over, they are giving salary only 10k(starting 6k salary , now 10k) Now, my mom is not feeling well and I couldn't afford medical expense as I am the only person earning in my family.. that too basic salary only.. keeping this in mind, I decided to quit the job here , but they told while joining , they won't provide experience certificate, if I quit the job in between...so without experience certificate , I can't join in any other company.. I got offer with decent salary in another company, but when I request my management for relieving in oral communication, they terminated me mentioned breach of contract without any warning(terminated on Dec 4 2020)....also they are saying that they can't provide me relieving letter or termination letter. but in my new company they are asking for relieving or termination letter. How can I handle this?