unsatisfactory service

I have Nokia Lumia 520 smartphone which I took out on contract almost 2yrs ago & I never had any problems with the device until a few weeks ago. I decided to send the phone in for repairs, along with my Blackberry 9320. My phone was sent to the head office repair center in JHB & I received it back on 2015-08-24. When I got to Cell C in Promenade Mall, I was told by the staff that the repair center said that the Lumia 520 was beyond repair because the PC board was bend as well as the charging pins but that they replaced the battery of the Blackberry which was out of warranty. I was confused by this & I demanded to speak to the repair center & Lebo told me that because of the above mentioned problems with the lumia & that it is out of warranty, my phone can't be fixed. I told her that the device is still under the manufacturer warranty & that if they explain how the PC boarded got bent then how can I. It was also the first time that the Lumia went for repairs but they replaced a battery which was almost a year old without any question. I would like a explanation for this as the Lumia has a few scratches but no other damages so I don't know how the PC board got bent.