Poor Service post online purchase

My sister upgraded our contracts online on the 7 December 2020 and we have not being getting the data as per the contract for 2 months, but paying a high amount. She has been calling since December and the query keeps being escalated for the past the month and we are nit getting any response. We also app**** for a modem and another cellphone contact for our parents on Black Friday and that has not been delivered or any updates given. It is the first time we are experiencing such poor service and look like it maybe time to switch service providers