Un-usable cell phone contract

Good morning, i'm so disappointed and embarrassed by the service i'm receiving. i got my mum a contract phone so that she can have enough resources to contact me as she is a person of ill due to age. in the beginning of June i've upgraded the contract to a new hand set and bigger monthly subscription. since i've done the upgrade she's unable to use the phone because i need to increase the credit i've calling almost everyday trying to do as per instruction but my call get cut off and only last week when i call they tell me that your call centers are not working.<br> <br> please i need a solution because i'm paying each and every month regarding that i'm not receiving any service