My acc.has been suspended after I payed double

On 27/09/15 my acc was suspended which made me very frustrated as I payed in advance when I payed end of Aug(paying for 22Aug & 22Sept)when I called them they reconnected the service but couldn't tell me why their system shows that I owe them whereas I've been billed R319.00 every month & I pay it without fail. I was told to send an e-mail, which I did the very same night but only contacted on 01/10/15 & was told that I owe R370 cause I've been paying R80.00 short which is very strange cause they send me a msg every mnth to remind me to pay R319 which is what I do. I asked the Lady(Vanessa who called me on01/10/15) to call the Manager as she couldn't assist me, she then kept me holding for 20mins then told told me Collen Niri(Manager) is in a meeting but will get back to me before end of that day, its now 5days later I'm still waiting for his call. Again today 06/10/15 my acc.is suspended without the explanation I'm waiting for frm Collen to tell me why do I have to be penalised for their mistake ? (They are the ones who told me to pay R319.00 & I did just that, & now they tell me I was suppose to pay R399 for the past 3mths & must pay for something I never knew about) plz help