Pathetic customer service

So I took my Samsung S4 cellphone to the smart centre to repair the screen-the phone had fallen and cracked, only to be told that I need a proof of purchase or copy of the contract. The IMEI number apparently showed that the phone was over two years old, which it wasn't. The reason this ****ed me off is because I know someone who took his phone in for a screen repair a few months earlier and his phone was fixed with no paperwork requested. Also, the S4 was a gift and the papers would not be easy to source. After a good few weeks, the proof of payment had been sourced and I took the phone to the smart centre once again. Only to be told that they do not ACCEPT THE PROOF OF PAYMENT FROM THE RETAILER where the phone was purchased-how was I supposed to know there were accepted retailers?? The manager, Chris, couldn't offer up any solutions, except to call someone to ask if there had been any repairs linked to the IMEI number, which there had not been. Furthermore, no solutions. After asking me for proof of purchase and then telling me it's not good enough..seriously?! I think this is absolutely pathetic service delivery, especially from a company as huge as Samsun