Cognizant — Content of the service letter issued

Address: DLF building Hyderabad

They asked me to resign saying that I have failed the BGV so i would have to resign. Even after my previous employer verifying the document and email ID they told that the BGV has failed. I resigned as instructed and surrendered the assets and ID card. After that i received a service letter that says that I have been terminated due to the failure of BGV. And before resignation the HR told me that it would be a regular resignation and nothing would reflect in the relieving letter. I have an offer in another company but due to this letter they aren't hiring me. Please help me. This one letter will become a remark on my career. All these years of hardwork would just go in vain. You need to understand that you people cannot play with my career like this. I even have the email proof of my previous employer verifying the document.