Cannot cancel contract

Good day, I left South Africa at the end of April thinking my number would be available for use in the UK despite me arranging this a month before I left, regardless I am now using my UK number. I have tried getting in contact with the customer care to cancel existing contract, the email response received stays to use the chat bot. The chat bot does not help with any form of cancellation. I then tried speaking to someone over Facebook who asks security questions and when given then asks for more and then more. Can someone either call my UK number to get this contract cancelled or communicate by email to sort this out as my line was not opened for use in the Uk by yourselves. I am going to put a stop payment in place should no feedback be received in 24 hours