Useless Service

I cancelled a contract with RAIN for a 5G contract which I didn't have coverage within a few days then I changed to the 4G Unlimited plan, I've paid my bills on time and now all of a sudden RAIN is claiming I have used data on the 5G and was me to pay for both contracts, every few days I've phoned them and a team leader gave me his word he will get back to me and resolved the issue, nothing has been done and RAIN are claiming for both contracts, they have take the router and cancelled the 5G card. I am waiting as all I get is emails and no one bothers reads what the email says and tries to fix the problem.