Worst Experience On last days - Senior Executive Operations Worldline Employee Review

Recently Left worldline below is my exp. When I resigned they manager said adjust 15 days I will allow you to leave early only 15 days. No need to pay for 15 days On my last day suddenly my manager said we will leave you 15 days early so you need to pay , but pay only 7 Days and he put 7 days on my Exit formalities form and sign on this. After I left organization got mail from HR and in attached FNF document 15 days salary will deducted. I contacted manager and mail to HR they said its policy and manager said HR is doing anything now we cant do anything on this.