Poor service

I have never been so disappointed with a service provider before like MWEB zyxel- I was paid for the service online March but my installation only took place on the 28th of March. On the 6th of April my router is switched off , and I am told I owe when I haven't even used the service for even 30 days.its difficult to get ahold of the call centre as you wait till you run out of airtime,I sent emails with no response. No explanation as to why my router is off.