Fix your billing system!!!

I activated rain in November last year while they were having a promotion for a free first month, in December I requested for my service to be cancelled as it was not working when I was home at all I had no connection and when I was at work it was really slow, in January they tried to debit me close to R600 and were unsuccessful because I knew I had cancelled the service and was expecting a debit for 1 month R300, in Feb they tried to debit an even higher amount, I tried to call the 081 number countless times with no success of reaching a consultant, today I went into the app to make a payment for December usage and I find an amount of around R1600 and when I look at the details on manage your account its showing bills from November till April and I haven't used the data since December. What am I expected to pay for? The sim card has had no network for Jan and I'm extremely unhappy with the service.