Salary not according to appointment letter

Dear Sir, I am Akash Singh from Jaipur, (basically from UP) i am working in a private Ltd. company based at Indore(M.P.), i have joined company on 4th January2016 at Indore headquarter . I start working in indore after 15-20 days company asked to me go for rajasthan , then i was ready to go rajasthan. At the time of joining company issue me appointment letter, in that my CTC Rs. 3.12 PA, Rs. 26000 per month and after PF and Other deduction it will be Rs. 23367 per month. In feb I got my 1st month salary Rs. 18490 Feb salary Rs. 21740, March salary Rs. 21690, and April Rs. 22790. When i got feb salary then i mail to company why it comes less but they not give any reply, i mail again then HR said that due to some confusion it come less but from next month it will come properly and arrear of 2 months will come with coming months salary. And when i got my march salary rs. 21690 then i again call to HR and then they said that your salary was revised and it is Rs. 24260( NO PF ) and other deduction, which is not clear. They changed my salary and not gives any information to me. Not give any new appointment letter or mail regarding it. In this salary they are not giving PF. They are not providing salary slip. Kindly guide me sir, i am very tensed due to it.