Useless Telkom

I cancelled my home Telkom line in March last year but Telkom still kept billing me.I then cancelled it again in November 2017 and got a reference to confirm cancellation yet they still bill me.The reason I cancelled is because I could not get the line fixed.if they check their records they will see the line has not been used in almost a year.I refuse to pay anymore bills for this account.I have tried putting a complaint in but my emails just get bounced back saying the complaints email box is full.How must I proceed from here.They seem to want money for no service