Poor service and poor network connection

I started subscribing with Smart Technology Centre in December 2021, ever since my network has never been stable, it drops calls which makes it a nightmare for us because we work from home. I have been dealing and in contact with Yolande Van Rensburg who sent her technicians a few times to my house but not finding a solution. The last straw was when she wanted to charge me a R1500 call out fee for one of her "Snr Engineers" to come out to my house. I refused to pay because I did not break anything within the network, why must I bear the costs if their connections never worked from the onset, they are even aware of this. All I want is for the services I pay for to be restored, working and in good quality as per their SLA. How is it possible that one household runs off two separate networks but with one Service provider? What they did on installation was to build on top of my former service provider's line, I questioned this and never got proper answers. This clearly leaves me questioning the caliber of this company. Both my wife and I wrote in and sent Yolande emails and she chose to ignore them as she has not responded to either one of us. I need this sorted by Smart Technology, I pay a lot of money to them monthly and I am expecting fairness and service I am paying for.