Why is it so difficult to buy a replacement battery for a mobile phone from Samsung

I am a disappointed Samsung customer. I run an NGO in Paarl called The Clothing Bank Winelands. We use a Samsung Neo Trend to contact the women who are on our Enterprise Development Programme. There is nothing wrong with the phone (it is now 2 years old) but the battery needs replacing. To save costs we would rather replace the battery than buy a new phone. However, one cannot buy a replacement battery for this phone (battery - SMG313H) over the counter at any mobile store or at a Samsung Store . I was thus directed to the mobile repairs section of the store to order a new battery. I have have been trying to do this from the Samsung Store in Tygervalley for 2 months now without any success. The staff at the store insist that I have to book the device in in order to have the battery replaced. There is nothing wrong with the phone so I do not want to book it in as it means we will be without a phone for the NGO. I was told by the staff they need to get a quote/invoice from their Technical Manager so that I can pay for this upfront and they can order the part. After 2 months I am still waiting for the quote/invoice. I was given the mobile contact number of the Technical Manager Robin and told I need to get him to give me a quote. His English is poor so communication has not been easy. Despite numerous assurances that he will send me a quote/invoice I am still waiting. So I now have no choice but to waste money and buy a new phone as I cannot buy a battery from Samsung. Why is it impossible to buy a replacement battery from Samsung without booking in the device???

Tracey Collins