Bad cell c service

Today I received a call about the network issue I logged a few days ago, where most of my incoming calls goes to voicemail. The person tells me I must change to roaming. Right, I tried it, and it didn't even work, my sim isn't allowed. To make it worse, they can't even investigate or tell me the cause. I'm still without an answer or solution. I get the excuse that there isn't enough towers. Great customer service I didn't expect from cell c!!