Purchase of simcards - Consumer Complaint for PEP STORES

Good day, I just want to understand what is the difference between a proof of address from the municipality and from the accounts/billing address? I went to Barkly West Pep stores to purchase an LTE TELKOM simcard but they refused to help with the proof of address from my clothing account. They said they can only help me with the proof of address from the municipality. That's why I want to know the difference between the two. Whereas my sister who resides in Jhb went to festival mall pepcell in kempton Park with her clothing account as proof of address and was able to purchase the simcard. Please let me know why am I not receiving the same service at the smallest town in SA? Where pep store is the only shop that sells simcards?