Retentions/Cancellations pathetic

I have been trying to get my contract cancelled for months already. Still not succeeded. My requests has been on email and they take up to 14 days to respond just to say it has been sent/escalated to the retentions/cancellations department who will contact you of which last reply from them was 22nd June 2020. No one has called yet!!! they do mention that you can phone 135 from your phone but I work full day and am not able to use my phone during the day.