Very unhappy Cell C customer

We have upgraded our contract (my husband and I) during May 2019 whereby Cell C sent us 2 x IPhone 7 phones. Upon receipt of the phones we decided to only take the one and cancel the other one (upon the telephonic upgrade they did say we have 14 days whereby we can decide and return if we changed our mind). We immediately phoned them to explain that we want to cancel the one and returned it. We really struggled with this phone call as we got cut off every time someone tried to put us through to another department. Eventually after two days of trying the said that they would send the courier to come and collect the phone (it was unopened even the courier bag was still sealed). After more than a week they still didn't came to collect. We have tried numerous times to call and find out why they didn't collect yet, but with no luck. Eventually we went to out Cell C store in the Secunda Mall and asked for their assistance. They said we must leave the phone there and they will contact them to collect it. Eventually RAM couriers collected the phone from the store on the 20th of June 2019. Ever since this we are still trying to get the contract cancelled as they say that they have not yet received the phone. If we phoned 50 times it is little, we phone and phone and they transfer ou from the one department to the other, every time you are cut off and have to start again. The local store couldn't assist as my husband had to phone as the phone contract is on his name. I need to upgrade my contract but cannot as this one is still not cancelled. We have been paying for a contract the last 3 months and we don't have a phone to use. Their service is pathetic. I need to get this resolved and I need to get them to cancel my contract immediately. I have the proof of the courier singing upon collecting the phone. I am sick an tired of phoning them as you do not get any satisfactionary assistance. Their service stink.