Probation period closer and consequential effect

Sir, I was promoted to the post of Assistant General Manager, on 14.06.2016 the was separate grade of pay from previous one. In the promotion letter it was clearly mentioned that you will on probation till date of retirement. I retired on 28.02.2017. The increment due on 1st January, 2017 was not granted. No formal letter for completion of Probation or otherwise is issued till date. The last increment was on 1st January, 2016 in the previous scale of pay. Kindly suggest remedies available to me.