overbooked flight

I was booked on flight SPA (AZ) 856 from Milan to Johannesburg via Abu Dhabi on the 16th of October,<br> I arrived in Abu Dhabi ( a woman travelling alone) at 6.15am, and at departure time at 9.30am, I was told they had overbooked the flight and I would have to wait 24 hrs for the next flight. They gave me 3 meal tickets and told me to hang around. I asked to be put into the executive lounge, so I would have a place to at least sit comfortably and be able to recharge my phone to let my family know where I was, I was refused this request and told they had already filled there quota. I then asked where I could redeem the meal vouchers and was told to go to any place up the escalator, I went up the escalator and sat down at the first restaurant and ordered a meal, after finishing I gave my voucher, just to be told it was not valid there. Thus I spent the rest of the day very unhappy in the waiting area for my flight. One of the worst experiences of my life, and was extremely badly treated. I then also missed my connecting flight between Johannesburg and Port Elizabeth which they were not prepared to refund.