SADV bad customer service for installation problems

Good day, I have been having installation problems with my router or modem it doeast switch on, the called Vuma call center for assistance and they referred me to so called IFP which is a network provider SADV. I they do not have a contact number but only a whatsup number, I tried contacting them using whatsup but the is no help at all, I tried using their email is not working. This is so disgusting because I am a good paying customer and yet I receive a crab service, on the other hand my children are writing exam and they rely on the wifi to search for school exam preparations. May you please assist as I tried everything on their platform and I don't get anything from them.