Jet RCS employ identity *******

Yesterday was the 1st morning that I woke up in my family home in South Africa after being in UAE for work the past year. The very first email I wake upto is a letter of demand from Jet RCS stating that I owe them R3126 and that I must pay the installment. After many phone calls and driving to a local Jet store to sort out the issue on an account which I paid up and closed a few months ago, the only reply I got is that they will have it sorted in 21 working days. I am fearing for a repeat of this case of identity theft because I also paid up and closed my Markham account. Jet is ruining my vacation and family time.