Sudden change in Network speed

I called Cell C and advised of the problem with the network I am experiencing on my router. They said they would refer the matter to their network department. I called on Sunday 3 April. They tried to contact me on 7 April but I was unavailable. They tried again on 8 April so I answered and said I work so I am unavailable until 16:30. He advised that he could not call me after that hour. I work with clients and cannot take calls. If cell c were serious about my complaint, they would make a plan and call me when it is convenient to me. My reference for my complaint is *** and the person I spoke to was Godfrey Mahlatsane. Either they sort out my network problem when it is convenient for me, or I lay a complaint with Consumer Protection for services not received. I have already lost 8GB of data due to slow network and not being able to use my monthly allocation of data. One can only use as much as ones network will allow. Please note I am available before 07:30 in the morning and again after 16:30