Poor service

I app**** for ADSL in April, they came and installed it in May. When I did the online application I put in my banking details for them to debit my account. Which never ever happened, they suspended my line at the end of June due to no payment. I phoned in and asked them what was going on and they then informed me that there is no debit order loaded on my account. Come July still no debit order and line is still off, come August same story, I did a manual payment on the 20th of August, I gave them grace until 24 August phoned them and they confirmed that they received the payment on 21 August so I asked why my wifi is still off they then lodged a fault request, till to date it is still off. I received my invoice for September and surprisingly my installment is almost R1000 but my contract is for R645 a month. I'm sick of their poor service!!!!! I'd prefer a full refund and they can keep their **** wifi for themselves!!!!