Disappointed customer

My parents took out a contract on their name for my family by Vodacom. It costs about R600 a month for 1000G with the router. We had the router for a year and it just stopped working. We took it into Vodacom to be booked in and sent to customer care to be checked and was told that it would take about 7 working days. It is still under warranty. It was booked in on a Monday 14th October an so I understood that I would receive it on 21st or 22nd of October. It was only booked in on Friday the 18th October and it was only looked at the following Monday the 21st and would take another 2 to 5 more working days. My parents have paid for the month already and we spent R500 so far on extra data just so that my kids can do their online schooling. So now what happens to the data that we didn't use during the time it was being fixed. Do we just loose it? And we must BUY more data up until we get our router back. The sim card which has the data on cannot be used in another devise as it is link to the router. If the router is still under warranty, why don't they just replace it? We as customers are always on the loosing side.