Bad service

I took a wifi router with mtn in January,I paid for January &February, they told me that if I'm not happy I may return it to the nearest so. The wifi didn't work for the whole 2 months I paid for the services I never used😌now it is still February they refused to take back the router they say i must pay for March first.how could i pay for March while I'm canceling in February?there's no coverage where I want to use it.so mtn thiks must just donate my hard earned money to them for the wife that doesn't supply internet,why must I pay for March while the cancelation is in February? I won't recommend it to anyone,the only thing they care about is MONEY