I have an ongoing issue since June 2020 and none o...

I have an ongoing issue since June 2020 and none of your customer service seem to be able to sort it out!! I have spoken to at least 8 agents regarding this, all of which promise they are going to be the ones who will sort it out and yet I don t here any more from them!!!I am now at the end of my tether and wish to make a complaint and also wish to speak to head office.
Update: have now called head office only to be on the phone for 1 hr 20 mins and recorded message saying they will answer my call shortly!! Given up now!
Can someone please contact me before I turn to all my social media platforms, watchdog and Martin Lewis!!!