Bad network coverage a week after getting the SIM

I recently purchased a Rain Sim Card plus mobile Modem for it. I received it on 26 December. I only was able to start using it on Monday 28 December 2020. The whole week it was amazing then the debit order goes off on the first and now today I can't even use my wifi because there has been no internet. Struggling with 2 modems for the network to work from rain as I thought it could be the modems. Turns out it's the Sim card of RAIN. I have asked for assistance and no help. This is really bad service.