Vodafone — Vodafone Constant Harassment after Port Out request

Hello,
I have a Vodafone prepaid number, and due to constant call drops, inefficient customer support and poor data network, i had decided to port out.
The problem begins here, since the UPC has been generated, i am getting calls in almost every 10 minutes to explain the reason why i have decided to port out.
I tried explaining on a few calls, but the calls got auto disconnected after 5-7 minutes, and then i receive a call again to explain from a different executive. Worse is, when i explain a problem, they cross question details like the complaint number, when did you face the problem, whom did you talk to, was it resolved and eventually they try to put the blame on for not following up or raising a complaint.
Since morning i have received almost 15 calls from Vodafone, and i am already tired of disconnecting them.
This is very frustrating, and distracting and hampering my work. I cannot be constantly looking at my phone, especially knowing someone is going to call and trouble me for the same thing over and over.
I dont know what strategy is, if this is the way the customers are being attempted to be retained, then i am sorry i am never coming back to Vodafone.