Vodacom fibre is the worst

I had a fibre contract with vodacom and one day the fibre went off only at my house for more than a month. No one came out too address issue. Eventually I had to cancel the contract then they called to say I am owing the remainder of amount, I requested a credit of the month I had no connection, they said they will calculate and send me invoice. Then settle balance but I never received it. Then it was call after call explaining the same thing over and over. Alas I never received the credit to this day and now they are refusing to grant me the settlement letter. I requested the said invoice, they refused to send that as well.