Real salary in italy for an ESR

Dear all,

I am doing my phD in Italy with a Marie Curie ESR scholarship, I do not belong to an EU member country and I do not understand the laws in Italy at all, the contract they have given me is not clear at all and when I receive my payment it is a lot less than I expected, after months of asking and insisting on an answer, they gave me a vague answer about INPS fees, the calculations I could do are these:

€4013.88 is the amount of money the funder has given the University to pay my salary and associated costs. From the information I have seen, it looks as though the university have to pay Employer’s INPS Gestione Separata fees at 23.353% first. This leaves €3268 for your gross pay. They then deduct your Employee INPS Gestione Separata fees from at 11.677%. This leaves me with €2886 net pay.

Is that correct? Can they deduct from my salary what corresponds to the employer? 

I appreciate that someone who has gone through the same thing guides me, since I do not understand why there is so much problem on the part of the university in showing me clearly how they distribute the money.