Been trying to close this account since September

Since 08 Septemeber I have been struggling with RCS. I paid the account up in full, then struggled to close as they then said they owe me money. After about a month & a half, this issue was resolved. I got refunded my money in Nov, & was promised they would process my request to close the account. I then called again a few days later, & was told they can only process my request on 12 Nov, & would furnish me with the closure letter. Today I again called to do the same, as the agent told me nothing has been done on my account. Upon discussing my frustration with him, he advised he will send my closure letter, he had confirmed my email address. Now 4 hours later, I have yet to receive this closure letter. Could someone higher up the ladder please sort this out & close the account already? I have wasted so much of my time fighting with RCS & wasting my airtime trying to get this sorted, & I keep getting promised it will be done, but still hasn't been done. It's pathetic.