Contract query of mtn account

I have a 2 year contract with MTN of an Acer laptop and a Samsung tablet. By November 2014 I was charged R3200 on my account for both merchandise and on December 2014 I was charged R880. There has been no clear explanation on the fluctuation of the bill. The explanation from Miss Lizanne Williams from Kimberley Diamond Pavillion mall service provider was that she can't do anything while she is waiting for the RPL report. By January I paid R550 but my laptop and tablet have been giving me problems since last year October and they have been in for repairs more than 3 times. I also reported to the manger, Chantel Peterson but she never gave me feedback.