How to handle sudden service discontinuation after years of service?

I submitted a letter of discontinuation of services yesterday, offering three months' salary as per the clause in the offer letter, after 4 years and 10 months of service. I performed well and received a promotion within 3 years with two best ratings. However, for the past 1.5 years, I have been mentally harassed by the organization due to not being given an appropriate profile. I was assured of a suitable position, but now, suddenly, my services have been discontinued before the appraisal results.