Phone contract query

I took a contract phone last month August but that phone gives me headache, it always restarting itself and need me to start afresh as if is my first time using. I send an email to customer care of blue label since they said someone will get back to me even today I am still waiting for them. I don't want their phone anymore and my stress is they will debit money on my account every month. Plz help me to close this account and they should sent courier to come and collect their phone. Imagine new phone started to give you phone what about all those 24 months. Where would I be with no service.