Hello Grazyna, I am Keith, one of the experts on Just Answer, and happy to help you with your question.
This is an independent tax information site and your problem is with the HR department within the hospital. It is up to the payroll administration to unscramble the mess. Comments like 'this is the fault of the housekeeping office' don't wash, someone in HR must take the lead and sort the matter out.
I would suggest that, if you are getting nowhere then call in your local trade union representative to assist. I remember long ago when I was one of these our principle problems were getting administrators to do their jobs properly on behalf of individual members.
In reality though, now we are out of the 14/15 tax year, there is actually not much they can do. By now you will have received your P60 from HR and to correct errors may need to self assess for tax to get things correct. Any over payment of tax will be refunded and any underpayment is usually collected through the 15/16 tax code.
I do hope my answer has been of some assistance to you and shown you a way forward.