Absolutely Pathetic Customer Service

In December 2020 a stock invoice appeared on my statement, I have been calling Supersonic multiple times over the last few months trying to get this resolved but received no feedback or resolution. Last month I spoke to Mukelo (was quite helpful) who told me that the stock invoice was for a Yealink phone which I purchased on sign up and hadnt been paid for. I forwarded proof of payment for this and was informed that it would be allocated to my account. One month later and I receive a statement which still shows that my account is in arrears and the payment from 2 years ago still hasnt been allocated. I am absolutely appauled by the level of service I am receiving and tired of wasting my time on the phone with you guys.