Získejte odškodnění od Pakistan International Airlines (PIA)

Hi , i bought a return flight from Pakistan Internation airline in 703£ for Manchester to Lahore and traveled on 18May to Pakistan. Paid extra 100 pounds to change return flight date for 30th June. Airline changed that flight from 30th june to 3rd July without informing me at all . Then on 3rd july i kept checking with them and flight was on time but when i reached airport , saw that flight was cancelled. Went to their different offices to ask them to either refund me the money or arrange alternative flight as i had commitment at my work place to reach at certain date. Inspite of all the mental agony and no help from airline i bought a very expensive ticket from Qatar Airways and returned to Manchester. Pakistan international airline has not refunded me any money nor showed any care or help what so ever , i left them emails and contacted via phone . Nothing worked . Now i almost lost hope but then thought to fight for my right . I paid them my money , i want them to compensate and asnwer me for this mental agoney and stress and financial burden they put me through for not any fault of my own. Kindly guide me what to do to seek justice and make airline realise for their ill treatment . Kind Regards Muhammad