Incorrect billing.

I was double billed by Supersonic almost two weeks ago, I informed them of this error via their Whatsapp chat line and I was assured that the extra payment would be reversed back into my account. This has not happened and my follow up email queries have gone unanswered. When I follow up via the WhatsApp chat line I am told the money will be reversed but I am not given a turn-around time.

If my money is not returned I will have no option but to withhold payment until I have recouped the money due back to me. The lack of communication is extremely disappointing.