Atrocious service from Cell C C-fibre

I have been struggling since Jan with C-fibre. For 6 years no issues, but now a disaster. I changed all our equipment, thinking it may be that, but it wasn't. Then Vumatel came out (they've been here 3 times already, but Cell C has shirked any responsibility, and still not come on-site) and confirmed it is not on their side - they even replaced the CPE. Cell C insisted that I install the router recommended by them before they would send out a technician - I did that 2 months ago (with one supp**** by them). Since then empty promise after empty promise from Sabelo and Nokubonga to send out a technician. Absolutely atrocious service. And then to add insult to injury, their *********** billing department sends me a collections notice for a supposedly unpaid account - I pay by debit order, and there is always plenty money in the account.!!! My only option now seems to be to change ISP.