Constant Call Center Bombardment

I have two contracts with Cell C in my private capacity costing me an average of R2500 per month. Since one of the contracts had its birthday I have been contacted daily by the 084 145 call center ruthlessly soliciting more of my business. I have pleaded with the call center agents, I have spoken with their Facebook admin repeatedly. Every time their response is..... we have sent through your request to NOT receive direct marketing. Yet two weeks later and I still receive calls from Cell C daily! I naturally now answer the call and leave the agents to speak to the airspace on my desk but it is still a nuisance and huge irritation. Do I simply accept this?