Pep cell phone that I can't use

I bought a Telkom phone that is locked to Telkom service provider. I was not aware that it was not a work area. I tried to return it and was told that I could not return it. I had paid R749 using my Pep card around the 4th or 5th June. My daughter tried to return it to the store, and the manager recognized that I had purchased that phone. The major's phone is locked to Telekom and does work in my area of residence which is useless to me. I am appealing that this must be swapped to a different phone not locked to a specific network.