Why dont you answer phone calls?

HI, I've only had good reviews of this company as i am an existing customer. Unfortunately, in the space of almost 2 months now i have been trying to take another contract with Telkom mobile but i cant due to them not having stock. I went to the Tygervalley store where i gave my details in, told the lady to hold on to the last phone as i am waiting for my current contract to change over to prepaid so we can port my number to Telkom. She agreed, but as expected, when i arrive to port my number and complete the contract she says they out of stock! I've been contacting her via mail to let me know when there is stock (but its my initiative to find out if there's stock via mail)She doesn't reply after some days so i drive up to the store to be told the same thing... NO STOCK! I've been trying to call various stores to find out who has stock, but NONE of the stores answer, it always goes to voicemail, or store numbers don't exist. How can you provide after sales service if you cant even answer a phone call from a customer. It is most frustrating where i have to drive to each store just to find out if you have stock and i see workers in the backroom chilling instead of answering the phone