FnF settlement

On 30th November 2018, I resigned from XYZ company, as per company process, a hard copy of the resignation was handed over to business head & also applied/approved on HR portal. My resignation was accepted by Business head by signing the hard copy of the same & approving it in the HR portal along with HR and my seniors. As per XYZ company HR process & employment contract, I have served my notice period which came to end on 28th of Jan. As per the XYZ company HR exit policy, my exit interview was arranged by HR & I completed it on 21st January. During my notice period, I had 10 balance leaves with me. I wanted early relieving to join new company by adjusting available leaves. After requesting HR she suggested me to avail those leaves in notice period, accordingly, I had a discussion with Business head & my senior about this and Business head/HR approved my leaves in the notice period. Therefore I went on leave from 16th January and joined a new employer. XYZ(previous employer) is refusing to pay my FnF, instead, have contacted ABC(current employer) stating breach of contract/dual employment and have ruined my impression at current employer organization, without any prior intimation to me to do so. While I went through the joining letter contract, there has been mention of that I cannot join/involve in alternative employment services providing similar to those of XYZ(previous employer), my new employer deals in totally different nature of a business, not at all related to the previous employer. Kindly help me what can I do to recover FnF from my previous employer and to stop them from ruining my impression at my present employer. TIA