No feedback for cancellation

I took out a sim contract around end March/ beginning April. It was a data LTE Advanced contract. Upon receiving the sim card and inserting it in my router, I could not get service. I found out that I needed an LTE Advanced router. I called the cancellations department to inform them that I would like to have it cancelled and have another data contract taken out. They informed me that I do not need to cancel, they can just deactivate it and activate another contract. I was informed that they would call me back to get this done. I have not received any feedback since and whenever I try to contact that department I can never get through and end up being on hold for a long time.

Can you please have someone contact me urgently to sort this out, as this contract has not been used and I need another one activated. Thanks