Resignation: Compensation to company for short notice period given

I had resign on 23 March 2017 and my notice period is 2 months which means my last day should be on 22 May 2017. However, I have to leave the company early and my last day of serving fall on 15 April 2017. My understanding on in lieu of notice period mean I have to compensate the company for the balance of the period I'm not serving the company (16 April 2017 to 22 May 2017), which is about 1 month 7 days! However, the letter from my HR stated I need to compensate 2 months to the company, is this right?

Did you inform them you leave prematurely? And they accept it in writing? Was there a proper handover of your duties.

There has been a breach of employment contract by yourself by leaving prematurely even if have tendered your resignation.

as long as you hand in official reaign letter,  you may leave by paying that 1 mth 7 days notice in lieu. however, it is best to wrte in also to notify yr wilingness to pay  this short notice and ask for exact amount to pay. 

calculation of short given notice a bit technical. the company has no right to stop tou from leaving once you compensate short given notice.