Please Cancel my Subscription and delete me on your system please

Please Im getting irritated by everyday calls that I get from rain call center, from Couriers and aĺl that Rain, I cancelled my subscription with Rain the beginning of April then at the end of april I went and dropped the router at Roodepoort brand ( which is in Hillfox) as to finalise my cancellation, what I dont understand is why do they keep on calling me wanting to collect the router and why do I stil get messages that I need to pay while I no longer use their service, please Rain sort this out Im tired of this please.