Please refund all my money you took for a router i never used.

I was old an MTN router contract for 15G @189 per month. I received the ****le on 03 April and called to cancel on 09April because I wasn't happy with the service. I was told to return it to MTN Mall of Africa and I did that on 14April and got an IRMS number. On 15April I called their Rewards Sales contact number and spoke to Lea Rampahsad who advised me of their 21 working days device cancellation turnaround time. This contract debit order went through in end of April, end of May and ia just received a statement that it will go through in end of June. i had this thing for four days but they are still debiting me after 3 months,,,,WHYYYYY??????????